signalling design: production guidance - rssb iss 1.pdfsignalling design: production guidance...

This document is the property of Railtrack PLC. It shall not be reproduced in whole or in part without the written permission of the Controller, Railway Group Standards, Railtrack PLC. Published by Safety & Standards Directorate, Railtrack PLC, Floor DP01, Railtrack House, Euston Square, London NW1 2EE © Copyright 1998 Railtrack PLC

Railway Group Code of Practice GK/RC0701 Issue One Date October 1998

Signalling Design: Production Guidance

Synopsis Guidance on the production processes to enable the design of railway signalling systems to meet the requirements of GK/RT0201.

Submitted by Anthony Sutton Standards Project Manager

Authorised by Richard Spoors Controller, Railway Group Standards

Withdrawn Document Uncontrolled When Printed

jtrousdale

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Signalling Design:

Production Guidance

R A I L T R A C K 1

Railway Group Code of Practice GK/RC0701 Issue One Date October 1998 Page 1 of 191

Contents Section Description Page

Part A

Issue Record 3 Distribution 3 Health and Safety Responsibilities 3 Supply 3

Part B

1 Purpose 5 2 Scope 5 3 Definitions 5 4 Design Process 26 5 Design Documentation and Content 26

Part C Design Specification Guidelines 1 Production Method 29 2 Acceptance 29 3 Format 29 4 Review and Changes 35

Part D Design Record and Production Control 1 Design Media 37 2 Security 38 3 Production and Record Copies 40 4 Production Processes 42

Part E Verification Process 1 Checking Overview 47 2 Design Tool Verification 48 3 Check Recording Methodology 49

Part F Operating Requirements Review 1 Scheme Plan Facilities 53 2 Interlocking Requirements 55 3 Signalling Control and Display System 55 4 Other Scheme Pre-Approval Issues 56

Part G Design Modifications 1 Categories of Design Modification 57 2 Modification Sheets 60 3 General 62

Part H Certification Process 1 Design Production 63 2 Production Issue Copies 63 3 Updated Records 64 4 Record Issue Copies 64 5 Approval and Issue Record Sheet 64 6 Issue Documents 64 7 Variations 65



2 R A I L T R A C K


Part J Source Record Updating 1 “One Drawing” Method 67 2 "Two Drawing" Method 67 3 Updating Resulting from Modifications 67 4 Update Control 68 5 Updating of Scheme Plans 68

Part K Configuration Control 1 Identification 69 2 Indexing 71 3 Change Recording 73

Part L Design Production in Special Cases 1 Control Measures 81 2 Temporary Work (Major) 81 3 Non-Conceptual Work 83 4 Presentation of Partially Commissioned (or Out of Use) Design Details 84

Part M Arrangement and Presentation 1 General Arrangement 87 2 Colour Presentation 87 3 Layout Plan Convention 88 4 Control Tables 90 5 Circuit Diagrams Convention and Nomenclature 91 6 Nomenclature for Cables, Wires and Terminations 99 7 Recording of Equipment Specification 100 8 Analysis 101

Part N Minimum Requirements for Design Details 1 Documentation Required for Approval in Principle 103 2 Level Crossing Ground Plans 123 3 Control Tables 127 4 Engineering Details 128 5 Operational and Maintenance Details 161

Part P Dependability 1 Introduction 167 2 Reliability 167 3 Availability 167 4 Maintainability 168 5 Safety 170

Part Q Occupational Safety 1 Construction (Design and Management) Regulations 171 2 Design Requirements for Occupational Safety 171 3 Health and Safety Information 172 4 Risk Assessment and Control 172

Part R System Safety 1 Introduction 177 2 Risk Assessment 177 3 Documentation 185

References 189


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Part A Issue Record

This Code of Practice will be updated when necessary by distribution of a complete replacement Part A and such other parts as are amended.

Amended or additional parts of revised pages will be marked by a vertical black line in the adjacent margin.

Part Issue Date Comments Part A One Oct 1998 New document, incorporating Part B One Oct 1998 guidance material from Part C One Oct 1998 GK/RT0201, Issue One. Part D One Oct 1998 Part E One Oct 1998 Part F One Oct 1998 Part G One Oct 1998 Part H One Oct 1998 Part I not used Part J One Oct 1998 Part K One Oct 1998 Part L One Oct 1998 Part M One Oct 1998 Part N One Oct 1998 Part O not used Part P One Oct 1998 Part Q One Oct 1998 Part R One Oct 1998 References One Oct 1998

Distribution This Code of Practice should be made available to all personnel who are involved in signalling design work.

Health and Safety Responsibilities

In issuing this Code of Practice, Railtrack PLC makes no warranties, express or implied, that compliance with all or any Railway Group Standard or Code of Practice is sufficient on its own to ensure safe systems of work or operation. Each user is reminded of its own responsibilities to ensure health and safety at work and its individual duties under health and safety legislation.

Supply Controlled and uncontrolled copies of this Code of Practice may be obtained from the Industry Safety Liaison Dept, Safety and Standards Directorate, Railtrack PLC, Railtrack House DP01, Euston Square, London, NW1 2EE.


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Part B 1 Purpose

This Code of Practice sets out guidance, in support of GK/RT0201, for the production of signalling design detail to ensure:

a) safe development and design of new and altered signalling systems impacting on Railtrack controlled infrastructure;

b) safe interfaces between all parties and systems; c) design details are prepared and presented clearly, accurately, consistently

and unambiguously; and d) client's specified requirements are met and the design is fit for purpose.

2 Scope This Code of Practice provides guidance on:

a) the design of signalling works applicable to the infrastructure; b) the design of signalling systems, whether lineside or train-borne; c) the design of software and data used in programmable signalling systems;

and d) the tools, including software, used in design.

It applies from scheme conception to acceptance into service or, where applicable, to decommissioning and disposal.

The design parameters and type approval processes concerning individual physical components used in the systems are dealt with in GK/RT0104.

The technical content of design detail is the subject of GK/RT0206 and GK/RC0706

3 Definitions In the definitions that follow, a word or group of words in bold type refers to another entry providing further information. Any reference to source indicates that the definition has been taken from an external document.

A glossary of general signalling terms is given In GK/RT0002. Those terms are not repeated here, except where they have been given a more technical definition for use within this Code of Practice. Where no definition is included in this Code of Practice, that given In GK/RT0002 should be used.

Safety terms are defined in GH/ZC0002.



6 R A I L T R A C K


TERM DEFINITION

930 SERIES (relay) A miniature plug-in relay in one of the following styles (see GK/RT0330):

930, 931, 932, 933, 934, 935, 936, 937 938,939, 940, 941, 942943, 945, 946, 947, 949, 960, 961, 962 963, 964, 966 (all variants) or 968.

A.C. ELECTRIFIED AREA An electrified area equipped for a.c electric traction; including a buffer zone, where the track circuit equipment is immunised against the a.c. traction frequency, extending generally for at least 3000m along any lines equipped solely for d.c. traction.

A.C. IMMUNE RELAY A d.c. relay which is immune to operation by a.c. of specified voltage and frequency.

ABNORMAL (conditions) Extreme loading on a part of the railway system (e.g. as a result of extended delays on one part of the service impinging on another). [source: RSPG]

ACCEPTABLE (risk) Associated with a risk that is either:

• tolerable AND as low as reasonably practicable; or • negligible

as defined in Railtrack's Railway Safety Case

ACCEPTANCE (product or engineering details)

The status given by Railtrack before use is permitted.

ACCIDENT Unplanned, uncontrolled event giving rise to death, injury, ill-health, damage or other loss.

ALTERATIONS Changes to existing installations (including the provision of new signalling) which form part or all of a self contained scheme. A single alteration is by definition one which is designed to be commissioned on a single occasion.

AMENDMENTS Changes to the design details which are required to be carried out as a result of a change in scope of the original specification. These should generally result in an amendment to a scheme plan.

ANTI-PRESELECTION The prevention of preselection of a signalling function, thus maintaining the protection of the signalling system should a wrong side failure occur

APPARATUS A product with an intrinsic function intended for the end-user and supplied or taken into service as a single commercial unit. [source: EMC Regs - modified]

APPARATUS CASE An apparatus housing which is intended for unprotected outdoor use, is smaller than a building or REB and is usually capable of being transported as a made-up unit. It is usually of metallic construction. The wooden equivalent is commonly known as an apparatus cupboard

APPARATUS CUPBOARD An apparatus housing which is intended for unprotected outdoor use, is smaller than a building or REB and is usually capable of being transported as a made-up unit It is usually of wooden construction. The metal equivalent is commonly known as an apparatus case.

APPARATUS HOUSlNG This is provided to house relays and / or other equipment at lineside locations or inter-lockings, and may consist of an apparatus case, apparatus cupboard dis-connection box, equipment room, REB, signal box, control centre, or other equipment building.

APPLICATION CRITERIA Document(s) specifying the constraints applied to the installation and maintenance of a system or an item of equipment in order that if can be guaranteed to deliver the performance attributes stated in the system or equipment specification.

APPORTIONMENT A process whereby the dependability elements for a system are sub-divided between various items which comprise the system to provide individual targets. [source pr EN50126]

APPROVAL The status given by the requisite authority when the product or works complies in all respects with the specification and addresses all identified risks.

APPROVAL IN PRINCIPAL The status given to a signalling scheme when the Scheme Plan is approved.

APPROVED FOR CONSTRUCTION

The status given to engineering details by the responsible design engineer following acceptance by Railtrack.

ASSESSMENT The undertaking of an investigation in order to arrive at a judgement, based on evidence, of the suitability of a product, competence of a person or acceptability of a risk. [source: pr EN50126 expanded]


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TERM DEFINITION

AUTHORISATION The formal permission to use a product within specified application constraints. [source: pr EN50126]

AUTOMATIC FUNCTlON A signalling function that, under ordinary operation, is operated automatically by the passage of trains and is not interlocked with any other signalling function. The function is generally associated with a particular signal box from which its operation is supervised, unless some form of local monitoring is provided.

The state of the function when there are no trains present is designated normal.

AUXILIARY (optical system)

Duplicate lamp or filament on hot or cold stand-by.

AVAILABILITY The probability that a system will be able to perform its required functions under given conditions at a stated instant of time or over a given time interval assuming the required external resources are provided. [source: ENV50129)

AVAILABLE The state of an item when it is capable of performing its required functions in the defined condition of use. [source: BS 4778]

BACK (B) CONTACT A contact of a relay which is made when the relay is released and broken when it is operated.

BACK FEED An inadvertent feed which has arisen at an intermediate point within a circuit due to the uncontrolled combination of positions of several pieces of control equipment.

BASIC EVENT See fundamental cause.

BEARER An item of steel or concrete of non-standard dimensions used to support the track in switch and crossing (S&C) areas. (See also sleeper and timber)

BIASED RELAY A d.c. relay which only operates when a d.c. supply of the correct polarity and voltage is applied to the coil.

Otherwise referred to as a 2-position polarised relay.

BONDING PLAN A detailed plan of the track layout showing individual rails and position of IRJs, together with track circuit feed and relay connections with polarities, cross bonds, structure bonds, impedance bonds, etc., as applicable. This term may also include track plans and negative Bonding Plans in d.c. electrified areas.

CABLE CORE PLAN A plan showing the allocation of signalling functions or systems to specific cores in multicore and data link cables.

CABLE ROUTE PLAN A layout plan showing the position of principal cable routes relative to signal boxes or interlockings and locations.

This plan is generally combined with the location area plan

CABLE SCHEMATlC PLAN A plan showing all signalling and power distribution cables required, together with sizes, to be installed between signal boxes or interlockings and locations.

CATCH POINT A point (switch and tiebar only), on running line gradients to de-rail wagons etc., running away in the wrong direction.

CENTRAL PROCESSING UNIT (CPU)

The central part of an electronic system or sub-system that manipulates data. It receives inputs from various interfaces, processes them in accordance with the control program and geographical data in the memory and returns the resulting outputs to the interfaces.

CERTlFICATE OF COMPLETION

Advice that works are ready for inspection.

CERTIFICATE OF COMPLIANCE

A statement of conformity to requirements and standards.

CERTIFICATE OF CONFORMITY (plant or equipment)

A statement of compliance with type approval.

CHANGE CONTROL See configuration control.

CHANGE-OVER CONTACT See dependent contact

CHECK RAIL See figure under switches and crossing.



8 R A I L T R A C K


TERM DEFINITION

CIRCUIT CONTROLLER A circuit switching device containing a number of contact bands, each of which may be individually cut to length and adjusted to make and break separate circuits at appropriate points in the cycle. The bands are operated by a mechanical device, such as a lever or signal.

CIRCUIT DIAGRAMS A collection of individual drawings showing the equipment layout and circuit arrangement associated with a location, an interlocking or signal box.

CLASS I EQUIPMENT Electrical equipment that requires the connection of the exposed-conductive-parts to a protective conductor connected to earth, to ensure personal safety. See also BS7671.

CLASS II EQUIPMENT Electrical equipment with double or reinforced insulation, either to prevent contact with exposed-conductive-parts, or to ensure no contact between such parts and live parts. The insulation is not therefore to be pierced by screws. Such equipment is never connected to earth. See also BS7671.

CLOSURE LIST Final Index of design details issued to the tester in charge.

CLOSURE PANEL (track) See figure under switches and crossings.

CLOSURE RAIL See figure under switches and crossings.

COMMON CAUSE FAILURE (CCF)

A failure which is the result of an event(s) which, because of dependencies, causes a coincidence of failure states of components in two or more separate channels of a redundancy system, leading to the defined system failing to perform its intended function. [source: IEC 1508]

COMMON RAIL The rail of a single rail track circuit that is electrically common to one or more adjacent track circuits or forms the traction return path where an isolated single rail track circuit is provided.

In non-electrified areas the common rail is bonded with track circuit bonding. In electrified areas the common rail is known as the traction return rail and carries the traction return current. It is therefore bonded with traction return bonding.

Also referred to as single rail or traction rail.

COMMON RAIL BONDING (CR)

A track circuit arrangement where only one rail (the Insulated Rail) is used with IRJs to separate the track circuits. The other ran (the common rail) is electrically continuous but is not used for traction return purposes.

COMPETENT PERSON A person who has the qualifications or certification, experience and ability necessary to perform a particular task. (See GK/RT0101)

COMPREHENSIVE APPROACH LOCKING

A form of approach locking on a signal, by which the approach locking is only effective when a train is approaching in order to afford maximum train operating flexibility. It uses look-back circuitry or logic to ascertain the line occupancy between a given signal at danger and the sighting point of the signal displaying the first caution aspect for the signal under consideration.

CONFIGURATlON (system) The structuring and interconnection of the hardware and software of a system.

CONFIGURATION CONTROL

A procedure to ensure that the functional and physical characteristics of a design or product are adequately identified and that changes to these characteristics are controlled and traceable throughout the life-cycle of the design or product, by recording its version or modification state.

Also known as version control.

CONSTRUCTION The carrying out of any building, civil engineering or other engineering work, particularly that which falls within the scope of the Construction (Design and Management) Regulations 1994.

Also know as installation.

CONTACTOR A relay with heavy duty contacts.

CONTINUITY BONDING Fishplate bonding specifically provided for traction return purposes, i.e. on non-track circuited lines in electrified areas, including non-electrified sidings, etc. Rail to rail bonding is required and cross bonding may also be provided.

It is denoted by the addition of a ‘ccc’ symbol on the bonding plan.


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TERM DEFINITION

CONTROL AREA The area of railway controlled or supervised by a particular signal box or control centre, as defined by the signalling Plan.

Also known as signal box control area.

CONTROL POINT A signal box (including control centre), gate box or ground frame (including ground switch panel or shunting frame).

CONTROLLED FUNCTION A signalling function that, under ordinary operation, is controlled from the signal box (or other control point) to which the function is allocated and may be interlocked with other signalling functions.

CORRECTIVE MAINTENANCE

The maintenance carried out after fault recognition and intended to put a product into a state in which it can perform a required function. (pr EN50126)

CORRELATION The comparison of the configuration and version status of a system with the design records to ensure that the two are in agreement.

CROSS BOND A jumper cable cross connecting the common rails or centre points of impedance bonds of parallel tracks to form a mesh of alternative paths, e.g. for traction return current.

CROSSING ANGLE See figure under switches and crossings.

CROSSING BACK See figure under switches and crossings.

CROSSING NOSE See figure under switches and crossings.

CUSTODIAN (of records) The organisation appointed by the infrastructure controller to take care of master records.

Also known as records custodian.

CUT-SECTION (location) Non-preferred term; see repeater location.

CUT-SECTION (track circuit)

A method of reducing the continuous length of a track circuit by the use of individual track circuits, each one controlling a common final track repeat relay, or equivalent. These are indicated as one track circuit on the signaller’s panel.

This is also known as a multi-section track circuit.

CUT-OFF CONTACT (relay) A front contact of a latched relay, internally wired in series with the release coil such that the coil cannot be energised unless the relay is in the operated position. Also known as economising contact.

D.C. ELECTRIFIED AREA An electrified area equipped for d.c. electric traction; including a buffer zone where the track circuit equipment is immunised against the d.c. traction voltage, extending generally for at least 3000m along any lines equipped solely for a.c. traction. (The distance is subject to specialist assessment and verification.)

DATA (signalling) Site specific geographical and control information in an electronic form, which may be of a safety-critical nature or otherwise. In order to be used in an electronic system or sub-system, data from master data files is usually permanently stored in an EPROM (erasable programmable read only memory).

DATA COLLECTION AREA The area of railway over which the train describer or IECC gathers information about train movements. It extends beyond the control area of the signal box.

DATA LINK A serial data transmission system.

In SSI systems, this refers to the link between the interlocking and the lineside location and may take the form of a baseband unmodulated trackside data link cable, or a long line link using standard telecommunications PCM equipment.

Internal data link cables are also provided between the modules in an SSI cubicle and, where applicable, between modules in adjacent interlocking cubicles.

DE-ENERGISED (relay) See released.

DEFECT See fault, defect, error, failure, mistake.

DEGRADED (conditions) The state of the part of the railway system when it continues to operate in a restricted manner due to the failure of one or more components. (source: RSPG)



1 0 R A I L T R A C K


TERM DEFINITION

DEGRADED CONDITIONS The state of the part of the railway system when it continues to operate in a restricted manner due to the failure of one or more components. (source: RSPG)

DEMODULATOR See modem.

DEPENDABILITY The ability of a product to perform one or several required functions under given conditions. See also RAMS. (source: pr EN50126)

DEPENDENT CONTACT A contact set which consists of a front contact, a back contact and one arm shared between them, with not more than one contact path made at any one time.

Also referred to as change-over contact.

DESIGN A wide term including specification and the production of drawings, design details and bills of quantity (including specification of systems or equipment). (source: CDM Regulations - modified)

DESIGN AUTHORITY Railtrack or such other organisation as is contracted by Railtrack to undertake specified design work on a system or on the infrastructure.

DESIGN DETAILS (signalling)

Any plans, control tables, engineering details and data, which are required to sufficiently define signalling systems and equipment for production or record purposes.

DESIGN RECORDS Design Details defining the current state of the infrastructure.

DISCONNECTION BOX An apparatus housing for unprotected outdoor use, which is intended to contain mainly terminations and is commonly smaller than an apparatus case.

DISPROVED WRONG SIDE FAILURE

A failure which was reported as wrong side but where the failure was conclusively shown not to have occurred or to have been a right side failure.

DIVERSITY A means of achieving all or part of the specified requirements in more than one independent and dissimilar manner. (source: ENV50129)

DOUBLE-COIL A.C. VANE RELAY

A double element relay with separate local and control (or track) coils which are required to attain a particular phase relationship for the relay to operate.

DOUBLE-CUT (circuit) The inclusion of controls in both feed and return legs in order to mitigate the risk associated with a false feed.

DOUBLE-JUNCTION The point of junction of two double track routes. It comprises two turnouts and a crossing.

DOUBLE-POLE (lamp) A double-filament lamp in which both filaments are connected permanently in parallel. (source: BS 469)

DOUBLE-RAIL TRACK CIRCUIT

A track circuit, either jointless, or defined by IRJs in both rails at all its extremities. On electrified lines, both rails carry traction return current.

DOUBLE-RAIL TRACK CIRCUIT BONDING (DR)

A track circuit arrangement where both rails are fitted with IRJs, or tuned zones are used to completely isolate a track circuit.

DOUBLE-WOUND A relay fitted with two electrically independent operating coils. Application of rated voltage across either coil causes the relay to operate.

DOWN TIME The time interval during which a product is in a down state. (source: pr EN50126)

DRACAS An acronym meaning Data Recording and Corrective Action System.

DROP-AWAY TIME (track circuit)

The time between the application of a shunt to the rails and the front contacts of track relay (TR) fully opening.

The converse is pick-up time.

DROP AWAY (DA) VOLTAGE (relay)

The maximum voltage applied to an operated relay coil at which the last front contact breaks.

DROP SHUNT The maximum value of non-inductive resistance which, when placed across the rails, causes the track relay to fully open its front contact.

DUAL ELECTRIFIED AREA An electrified area meeting the criteria of both an a.c. electrified area and a d.c. electrified area.


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TERM DEFINITION

EARTH FAULT DETECTOR A permanent device, wired to the busbars, that will detect an earth fault on the power supply and give an alarm that will alert the maintainer.

Also known as earth leakage detector.

EARTH FAULT LOOP IMPEDANCE

The impedance of the earth fault current loop starting and ending at the point of earth fault. (source: BS7671 extract)

EARTH LEAKAGE DETECTOR

See earth fault detector.

ECONOMISING CONTACT (lever lock)

A contact internally wired in series with the coil such that the lock coil is not energised when the lever is in the full travel position. Alternatively the function may be controlled externally (which is the only available method where cut-off is required at other than a full travel position).

ECONOMISING CONTACT (relay)

See cut-off contact.

ELECTRIC TRACTION ENGINEER

Engineer responsible for the electric traction fixed equipment.

ELECTRICAL SYSTEM An installation, identified by the relationship that the source and the exposed-conductive-parts of the installation have to earth:

• TN system: where one or more points of the energy source are directly earthed, the exposed-conductive-parts of the installation being connected to that point by protective conductors, either completely separate from the neutral or return conductors (TN-S), with the neutral and protective functions combined in a single conductor throughout the system (TN-C), or with the neutral and protective functions combined in a single conductor in part of the system (TN-C-S).

• TT system: where one point of the energy source is directly earthed, the exposed-conductive-parts of the installation being locally earthed, independent of the source earth electrodes.

• IT system: where there is no connection between the live parts and earth, the exposed-conductive-parts of the installation being locally earthed, e.g. an unearthed signalling power supply.

(source: BS7671 adapted)

ELECTRIFIED AREA An area of railway encompassing all lines equipped for electric traction, extended to include any non-electrified lines or sidings. The area also includes a buffer zone where track circuit equipment is immunised against traction interference, extending generally for at least 800m, or the length of two track circuits with double IRJs, whichever is the further, beyond the end of the electrified line.

See also a.c. electrified area, d.c. electrified area and dual electrified area.

EMERGENCY SITUATION A current unforeseen or unplanned event which has life threatening or extreme loss implications and requires immediate attention (e.g. a fire). (source: RSPG)

ENERGISED See operated.

ENGINEERING DETAILS (signalling)

Design details from which a signalling system is constructed.

EQUIPOTENTIAL BONDING Electrical connection maintaining various exposed-conductive-parts and extraneous-conductive-parts at substantially the same potential. It need not include a direct connection to earth. (source: BS7671 augmented)

ERROR See fault, defect, error, failure, mistake.

EXPOSED-CONDUCTIVE-PART

A conductive part of equipment that can be touched and which is not a live part but which may become live under fault conditions. (source: BS7671)

EXTERNAL (circuit or power supply)

Failing to wholly meet the internal criteria.

EXTRA LOW VOLTAGE See voltage, nominal.





TERM DEFINITION

EXTRANEOUS-CONDUCTIVE-PART

A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation, e.g. structural metalwork. (source: BS7671 augmented)

FAIL-SAFE A concept which is incorporated into the design of a product such that in the event of failure, it enters or remains in a safe state. (source: ENV50129)

FAILURE The termination of an item to perform a required function. (source: BS4778)

See also fault, defect, error, failure, mistake, common cause failure, random hardware failure, and systematic failure and fault, defect, error, failure, mistake.

FAILURE CLASSIFICATION Classification of a Failure as Right Side, Wrong Side, protected, etc.

FAULT TOLERANCE The attribute of an item that makes it able to perform a required function in the presence of certain given sub-item faults. (source: IEC 1508)

FAULT, DEFECT, ERROR, FAILURE, MISTAKE

The cause of an error is a fault (for example a hardware defect) which resides temporarily or permanently in the product. An error is that part of the product state which is liable to lead to a failure. A failure occurs when the delivered service deviates from the intended service. A failure is the effect of an error on the intended service. A mistake occurs when human action (at any phase of the life-cycle) may result in unintended product behaviour. (source: pr EN50126 modified)

FAULTING See corrective maintenance.

FEED Power Supply phase (BX) or positive (B) connection.

In some cases may be used as a composite term to incorporate both feed and return (e.g. track circuit feed).

FISHPLATE BOND Provided to ensure electrical continuity between two rails mechanically connected, e.g. by a steel fishplate, common chairs, or other bolted connection.

Also referred to as fishplate type bond, or rail joint bond.

FISHPLATE TYPE BOND See fishplate bond.

FIXED DATE See system program.

FREE-WIRED INTERLOCKING

A relay interlocking that comprises individually wired relays rather than pre-wired sets of relays.

FREQUENCY DIVISION MULTIPLEX (FDM)

A data transmission system that uses unique frequencies to separate channels over a single pair of conductors.

FREQUENCY ROTATION The sequential application of specified frequencies.

FRONT (F) CONTACT A contact which is made when the relay is operated and broken when it is released.

FUNCTIONAL EARTHING The connection to earth necessary for the proper functioning of electrical equipment, i.e. an earth return. This may be used for telecommunications purposes, but is no longer permitted for new signalling circuits. Conductors for functional earthing are identified by the colour cream. (source: BS7671 augmented)

FUNCTIONAL SAFETY ANALYSIS

Assessment of elements within a safety system to demonstrate that it attains the required safety integrity.

FUNCTIONAL UNIT An entity of hardware or software, or both, capable of accomplishing a specified purpose. (source: ENV50129)

FUNDAMENTAL CAUSE (failure)

A primary deficiency or prevailing condition which permitted the immediate cause to lead to a wrong side failure.

Also known as Basic Event.

GEOGRAPHICAL DATA Fixed information stored in EPROMs that configures an electronic system or sub-system to the requirements of a particular site.

GEOGRAPHICAL INTERLOCKING

A route relay interlocking in which standard pre-wired sets or relays are provided for each signalling function, arranged and electrically interconnected in a geographical manner.

GRACEFUL DEGRADATION

A means by which a more complex control sub-system has the facility to switch into some other (more restricted) mode of operation if a particular input fails, or if availability is otherwise reduced by some means.


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TERM DEFINITION

GUARANTEED POWER SUPPLY

See secure power supply.

HAZARD A physical situation with a potential for human injury. (source: IEC 1508)

HEADWAY CHART A time / distance graph based on standard braking and acceleration curves that may be used to determine optimum signal positions.

HEAVY (H) DUTY CONTACT (relay)

A relay contact that is rated to make and break a current of up to 30A. These generally have magnetic blow out to suppress the arc, but are not guaranteed to be non-weld and so the relay must be down proved.

HEEL (of switch) See figure under switches and crossings.

HIGH CURRENT D.C. ELECTRIFIED AREA

A d.c. electrified area capable of supplying trains with a peak total traction current in excess of 6.5kA.

IMMEDIATE CAUSE (failure)

A direct act, omission or equipment fault which triggered the failure.

IMPEDANCE BOND Special device which presents a low impedance to traction current and a higher impedance to track circuit current.

INCIDENT (near miss) An unplanned, uncontrolled event, which under different circumstances could have resulted in an accident.

INDEX (configuration control)

A listing of design details for the configuration control of signalling systems (including status record index sheets for software).

INFRASTRUCTURE CONTROLLER

A railway business which is responsible for the control and operation of the railway lines, including the track, structures, plant and control equipment. An infrastructure Controller may either own or lease the infrastructure concerned.

INSTALLATION (activity) See construction.

INSTALLATION (infrastructure)

That part of the signalling system associated with the infrastructure at a particular place.

INSULATED BLOCK JOINT (IBJ)

Non-preferred term; see insulated rail joint.

INSULATED RAIL The rail of a single rail track circuit that is fitted with IRJs to separate adjacent track circuits. The insulated rail is always bonded with track circuit bonding, as it does not carry traction return current.

Also known as signal rail.

INSULATED RAIL JOINT (IRJ)

A method of joining rail ends together whilst maintaining electrical insulation between them.

An alternative non-preferred term is insulated block joint (IBJ)

INTERLOCKING (building) The (generally dedicated) building housing the interlocking system, where separate from the signal box (or other control point).

INTERLOCKING (equipment)

The equipment that performs the role required of the interlocking system.

INTERLOCKING (system) The safety-critical locking provided between signalling functions in accordance with control tables.

INTERLOCKING AREA The area of railway controlled by a particular interlocking, extended up to a boundary with each other adjacent interlocking controlled by the same or another signal box.

INTERNAL (circuit) A circuit that does not leave the apparatus housing in which it originates and which is fed from a busbar which feeds only internal circuits. This includes the feed to an isolated transformer supplying an external circuit. Circuits that extend between adjacent apparatus housings may be considered to be internal if they are run in a protective non-conducting duct and are judged to be away from any environment that might be susceptible to earth faults.

INTERNAL (power supply) A power supply feeding only internal circuits. Also known as local power supply

INTOLERABLE (risk) Associated with a risk that is greater than the upper limit of tolerability, as defined in Railtrack's Railway Safety Case.





TERM DEFINITION

JOINT HOPPlNG Where fast moving short vehicles pass from one track circuit to the next, the difference between the pick-up and drop-away times can cause the vehicle to momentarily be undetected.

JOINTED TRACK ClRCUIT A track circuit whose extremities are defined by the use of IRJs.

JOINTLESS TRACK CIRCUlT

A track circuit whose extremities are defined by the use of tuned circuit techniques, The extreme limits of a jointless track circuit area are either defined by the use of IRJs or by the use of a tuned circuit between the rails.

JUMPER An interconnecting cable (commonly single core) between two termination points within an apparatus housing.

JUMPER CABLE (track

circuit / traction)

An interconnecting cable (commonly single core) between two pieces of rail that are not adjacent, for track circuit or traction purposes. This includes midpoint connections to impedance bonds.

JUNCTION INDICATOR (JI) A route indicator that has category one (long range) performance and displays the route at a signal by means of a line of white lights.

KEYBOARD An interface between an operator and a system facilitating the input of commands or data.

LAMP PROVING RELAY A neutral d.c. relay designed to operate from the current supplied to signal lamps and to release when lamp or lamps burn out. Some relays incorporate a bridge rectifier to operate from a.c. lamp currents.

LATCH A memory location that switches between two states, representing a particular signalling function. The states are commonly known as set and unset.

LATCHED RELAY A relay that switches between two states, representing a particular signalling function, and stays in the last set position when the operating feed is removed. The states are known as operated and released.

LEFT HAND RELAY The left hand half of a twin relay as viewed from the front. In a 930 series twin relay this controls the contacts in banks C and D.

LEVEL CROSSING GROUND PLAN

A scaled and dimensioned drawing showing the position of all equipment, utilities and associated features in the vicinity of the level crossing, and the detail necessary for engineering, operating and statutory requirements.

LEVEL CROSSING ORDER A statutory instrument describing the application of the RSPG to a specific level crossing. Formerly known as section order.

LEVER (OR SWITCH) NOMENCLATURE PLATE

A plate fixed to a lever or adjacent to a switch, describing the lever / switch function, together with ‘order of pulling’ details.

LIFE-CYCLE COST The total cost of ownership of an item taking into account all the costs of acquisition, personnel training, operation, maintenance, modification and disposal. (source: BS 4778)

Also known as whole-life cost.

LIKE-FOR-LIKE WORK The removal and restoration of an item of equipment (including a cable renewals), where the work does not require any update to signalling design details.

LINE CIRCUIT An external relay circuit, which is not an on-track circuit.

LINESIDE LOCATION See location.

LOCAL PANEL A panel (sometimes simplified) provided at the interlocking and capable of being used to take over control from the main panel at the signal box. It may also be used as a maintainer’s monitoring panel, when the operating function is not in use.

LOCAL POWER SUPPLY See internal power supply.

LOCATION A group of all signalling lineside apparatus housings (including buildings) at a particular site and the equipment contained therein. (This excludes apparatus housings that perform a main interlocking function, although some interlocking local to ground frames or level crossings may be included.)

Alternatively known as lineside location.


Signalling Design:

Production Guidance



TERM DEFINITION

LOCATION AREA PLAN A scale layout plan showing every signalling location, together with their identities, position and type of cases, interlocking boundaries, certain equipment identities (e.g. TFMs) and the area of signalling equipment that is controlled by each location.

This plan is generally a sub-version of the scheme plan or signalling plan.

LOW VOLTAGE See voltage, nominal.

LOW VOLTAGE ALARM See under voltage detector.

MAIN (optical system) Primary lamp or filament of a duplicated pair.

MAIN CABLE A twin or multicore lineside cable carrying signalling functions or power supplies between apparatus housings.

MAIN EARTHING TERMINAL (MET)

The terminal or bar provided for the connection of protective conductors, including equipotential bonding conductors, and conductors for functional earthing if any, to the means of earthing. (source: BS7671)

MAINTAINABILITY The ability of a product under given conditions, to be retained in, or restored to, a state in which it can perform its required function. (source: ENV50129)

MAINTAINED LOCKING An alternative to the term route locking. (see GK/RT0002)

MAINTAINER’S MONITORING PANEL

An indication panel situated at the interlocking that repeats the indications sent to the signaller and allows the maintainer to observe the state of the interlocking. It also indicates various fault conditions. This may be combined with a test panel.

MAINTAINER’S TERMINAL This consists of a VDU, keyboard and printer connected to a solid state interlocking, or an IECC system monitor sub-system. It is used to obtain essential fault diagnostic information and also acts as an interface with the system to enable restrictive controls on the equipment to be set.

Also known as technician’s terminal.

MAINTENANCE The combination of all technical and administrative actions, including supervision actions, intended to retain a product in, or restore it to, a state in which it can perform a required function. (source: pr EN50126)

MAINTENANCE RECORDS Design records kept on site for maintenance purposes.

MAJOR WORKS Any infrastructure alterations which are outside the scope for minor works.

MAKE-BEFORE-BREAK CONTACTS

A pair of relay contacts, where at each state of the relay only one of the pair is made, but which during transit momentarily have both contacts made.

MASTER RECORD The certified signalling design record from which duplicates are obtained for issue.

See also source record.

MECHANICAL LOCKING CHART

A plan showing the arrangement of mechanical locking components to achieve the mechanical locking control tables.

MECHANICAL LOCKING CONTROL TABLES

A tabulation of the locking between signalling functions associated with a mechanical lever frame.

MEDIUM (M) DUTY CONTACT

A relay contact that is rated to make and break a non-inductive current of 3A to 6A.

MESHED CIRCUIT Complex circuitry feeding more than one relay, where the same could be achieved by independent circuits, thereby requiring duplication of contacts. Not all paths in a meshed circuit are applicable to all relays.

MICROCORE A parallel data transmission system using a multicore cable having a large number of small diameter conductors. Interface buffer relays may be provided at each end.

MINIATURE ROUTE INDICATOR (MI)

An alphanumeric route indicator having category three (short range) performance (equivalent to the former stencil route indicator).

MINOR WORKS Infrastructure Alterations which are listed as such in HSE/HMRI Guide to the Approval of Railway Works, Plant and Equipment.

MISTAKE See fault, defect, error, failure, mistake.

MOD STATE See modification status.





TERM DEFINITION

MODEM An electronic device that converts a signal to make it suitable for transmission (modulator) or reception (demodulator) of information over a particular medium.

MODIFICATION STATUS The detail that defines the particular version of the design or specification, appropriate to the functional and physical characteristics of an item of equipment or system, and is recorded under configuration control procedures.

Colloquially known as mod state.

MODIFICATIONS Changes to the design details which are required to be carried out after they have been officially issued, usually as a result of installation, testing and commissioning activities.

MODULATOR See modem.

MONITORED (level crossing)

Checked by the observation of indications which provide the signaller with the status of equipment.

MOVEMENT AUTHORITY Permission for a train to run to a specific location.

MULTI-PROCESSOR MODULE (MPM)

The part of an SSI system that performs the interlocking. Each SSI cubicle contains three MPMs that control the signalling using a majority voting technique to ensure safety and availability.

MULTI-SECTION (track circuit)

See cut-section.

NEGLIGIBLE (risk) Associated with a risk that is less than the lower (broadly acceptable) limit of tolerability, as defined in Railtrack’s Railway Safety Case.

NEUTRAL RELAY A d.c. relay which operates with either polarity of supply to the coil.

NON-CONCEPTUAL WORK Work which is based directly on an applicable existing proven design and does not introduce new design features to a system.

NON-SAFETY-CONTACT A relay contact that is not a safety contact. This includes metal to metal contacts for medium duty use, where both elements are made of silver, silver cadmium oxide, or 60/40 silver palladium.

NON-SAFETY-RELATED A signalling function or sub-system where operational safety and the integrity of the interlocking are not directly affected. Manual intervention, where a failure would be noticed, may be part of the process.

Formerly known also as non-vital.

NON-VITAL See non-safety-related.

NORMAL (function) Position of a lever when it is fully back in the lever frame. The un-operated or quiescent state of a two-state system.

The converse is reverse.

NORMAL CONTACT A contact in a polar relay, which is closed when the relay is operated to the normal position.

NORMAL (conditions) The operating conditions which a part of a railway is designed to accommodate. This would include peaks, e.g. rush hours, and troughs in demand experienced during the day. (source: RSPG)

ON-TRACK CIRCUIT An external circuit run to, or via, an item of on-track signalling equipment in a tail cable.

OPERATE COIL A winding which when energised at the rated voltage and frequency, causes the armature of a relay to move to the operate position.

OPERATE TIME (relay) The time interval between the energisation of the relay coil and the first front contact making.

The converse is release time.

OPERATE VOLTAGE (relay)

The minimum voltage applied to a released relay coil at which the last front contact makes.

Also known as pick-up (pu) voltage.


Signalling Design:

Production Guidance



TERM DEFINITION

OPERATED (relay) The state of a relay when the armature is energised, picked up (PU), or latched, all front contacts are made and all back contacts are broken.

Also known as energised, and colloquially as ‘picked’ or ‘up’. The converse is Released.

OPERATING NOTICE DIAGRAM

A simplified layout plan for publication in, or with, the signalling alterations section of an operating notice.

OPTICAL FIBRE An optically transparent fibre consisting of a central core surrounded by a cladding of lower refractive index and used to transmit lights by means of multiple internal reflections.

ORDINARY ACTING (relay) A relay without a particular stated specialised operating characteristic.

OUT OF USE Non-operational equipment that is still connected to the infrastructure.

See also spare.

OUTLINE PROJECT SPECIFICATION (OPS)

A document listing the principal elements of proposed works.

OVERLAPPING DESIGN Design undertaken in a compressed timescale such that activities relating to different alterations which would usually be undertaken sequentially are undertaken concurrently. This is only permitted where one design engineer is identified as having overall responsibility for the interface between the successive design alterations.

OVERLAY TRACK CIRCUIT A track circuit which can be superimposed over another, neither having any effect on the other and both operating independently.

PARALLEL (bonding) The method of bonding rail sections with diverse parallel electrical paths for availability. track circuit bonding in this mode is non-fail-safe, since failure of a single jumper cable, fishplate bond, or IRJ will not necessarily release the track circuit relay, and hence could result in loss of vehicle detection.

PARALLEL DESIGN Design undertaken in a compressed timescale such that activities relating to the same alteration which would usually be undertaken sequentially are undertaken concurrently.

PARALLEL (data link) A means of data transmission by which many discrete bits of information are sent at the same time along a microcore link.

PICK-UP (PU) SHUNT The minimum value of resistance between the two running rails at which the track relay just closes its front contacts.

PICK-UP (PU) VOLTAGE (relay)

See operate voltage.

PICK-UP TIME (track circuit)

The time between the removal of a shunt to the rails and the first front contact of the track relay (TR) making.

The converse is drop-away time.

PIN-CODE See registration pin-code.

PLUG-IN The attribute of an item of electrical equipment which can be replaced without disconnecting any wiring.

PLUGBOARD The permanent mounting block and termination for external wiring, for use with plug-in equipment.

POLAR (relay) A relay with two operated positions (normal and reverse) and a central, released state. The operated position depends upon the direction of the current or phase of the current in the operating circuit. A polar relay may not have contacts in the Released position.

See also biased relay (sometimes referred to as a 2-position polar rely).

POLARISED CIRCUIT A circuit where the resulting operation is dependent on the polarity or phase angle of the feed.

PRESELECTION The selection of a signalling function prior to the conditions becoming available, so that it is automatically set when some other function is restored. This could result in a protected wrong side failure becoming unprotected.

PREVENTATIVE The maintenance carried out at predetermined intervals or according to prescribed criteria





TERM DEFINITION

MAINTENANCE and intended to reduce the probability of failure or the degradation of the functioning of an item. (source: pr EN50126)

PRIMARY FUNCTION RELAY

The relay by which the logic required to control a signalling function is brought together. It is the first relay in a chain that directly controls all safety-critical signalling functions. it is the only function relay which has back contacts valid for use in safety-critical functions.

PROGRAMMABLE LOGIC CONTROLLER (PLC)

A self-contained electronic sub-system that manipulates date. It receives inputs from an interface, processes them in accordance with the system program and geographical data in its memory and returns the resulting outputs to the interface.

PROTECTIVE CONDUCTOR A conductor used for some measures of protection against electric shock and intended for connecting together any of the following parts:

• exposed-conductive-parts; • extraneous-conductive-parts; • the main earthing terminal; • earth electrode(s); • the earthed point of the source or an artificial neutral.

Protective conductors are identified by the colours green and yellow. (source: BS7671 augmented)

PULSE CODE MODULATION (PCM)

A serial data transmission system by which many channels of information are passed over a data link, by use of a multiplexer.

QUARTZ HALOGEN LAMP See Tungsten Halogen Lamp.

RAIL JOINT BOND See fishplate bond.

RAIL SECTION (track circuit)

A section of one running rail continuously electrically bonded with its extremities defined by IRJs, and within which all continuity connections are by fishplate bonds. It may extend over several track circuits as the common rail) or only part of a track circuit.

RAMS An acronym meaning a combination of reliability, availability, maintainability and Safety. See also dependability. (source: pr EN50126)

RANDOM HARDWARE FAILURE

Failures occurring at random times, which result from a variety of degraded mechanism in the hardware.

Note 1) There are many degradation mechanisms occurring at different rates in different components and since manufacturing tolerances cause components to fail due to these mechanisms after different times in operation, failures of a total equipment comprising many components occur at predictable rates but at unpredictable (i.e. random) times.

Note 2) A major distinguishing feature between random hardware failures and systematic failures is that system failure rates (or other appropriate measure), arising from random hardware failures, can be predicted with reasonable accuracy but systematic failures, by their very nature cannot be accurately predicted. That is, system failure rates arising from random hardware failures can be quantified with reasonable accuracy but those arising from systematic failures cannot be accurately quantified. (source: IEC 1508)

RECEIVER (Rx) An electronic device that converts, filters or decodes into a discrete output, information that has been received from another site.

RECORD Information bearing media, irrespective of date or physical format, created or received in the course of carrying out the duties and functions of an undertaking, and subsequently retained by the undertaking or its successors as evidence, as a reference source, or to meet legal or regulatory obligations.

RECORDS CUSTODIAN See custodian (of records).

RED BOND A traction bond that has been designated as being dangerous to staff if disconnected. It is marked red to draw attention to its importance and to aid inspection. Special procedures are in place for the reporting of damage to a red bond.

REDUNDANCY The provision of one or more additional elements, usually identical, to achieve or maintain availability under failure of one or more of those elements. (source: ENV50129)

REGISTRATION PIN-CODE A series of locating pins assembled in a unique pattern to prevent equipment being incorrectly used. The unique pattern also acts as a means of identification for a specific style and variant of a relay.


Signalling Design:

Production Guidance



TERM DEFINITION

The term registration pin-code is commonly abbreviated to pin-code.

RELEASE COIL A winding which, when energised at the rated voltage, disengages the latching mechanism and causes the relay to release.

RELEASE TIME (relay) The time interval between the removal of the supply (at rated voltage) to the relay coil and the last front contact breaking.

The converse is operate time.

RELEASED (relay) The state of a relay when the armature is de-energised, dropped away (DA), or unlatched, all back contacts are made and all front contacts are broken.

Also known as de-energised and colloquially as ‘dropped’ or ‘down’.

The converse is operated.

RELIABILITY The ability of an item to perform a required function under stated conditions for a stated period of time. (source: ENV50129)

RELOCATABLE EQUIPMENT BUILDING (REB)

Apparatus housing to specification BR 1615 or equivalent.

REPEATER LOCATION A lineside location where all line circuits are interrupted by the provision of repeat relays for the purpose of limiting interference voltage.

Also known as cut-section location.

RESIDUAL VOLTAGE The voltage remaining across the rails or relay of a track circuit after the feed has been disconnected.

It may be caused by mutual interference between adjacent single rail track circuits, the battery effect of the track formation, cathodic protection measures, or d.c. traction return or other stray currents.

RESOLVED (failure) At the time of closure of the investigation, the engineer is satisfied that a fault occurred and the cause has been established.

RESPONSIBLE DESIGN ENGINEER

Person directly employed by the design authority who has delegated responsibility for the design, development, safety and dependability of an engineering discipline associated with an infrastructure project.

RETURN Power supply neutral (NX) or negative (N) connection.

The converse is feed.

REVERSE (function) Position of a lever when it is pulled fully forward in the lever frame. The operated state of a two-state system.

The converse is normal.

REVERSE CONTACT A contact, in a polar relay, which is closed when the relay is operated to the reverse position.

RIGHT HAND RELAY The right hand half of a twin relay as viewed from the front. In a 930 series twin relay this controls the contacts in banks A and B.

RIGHT SIDE FAILURE A failure which does not result in the protection normally provided by the signalling system being reduced.

ROUTE HOLDING An alternative to the term route locking (see GK/RT0002).

SAFE STATE Any one of the following:

• the state of the last valid request at the interlocking; or • correspondence with the state of the trackside equipment; or • the most restrictive state.

SAFETY CONTACT A relay contact that is specified for safety purposes in the 930 series specifications. These are non-weld contacts, generally silver to carbon for ordinary use. For medium duty use, the contact elements may be of silver impregnated graphite (SIG) and silver.

SAFETY-CRITICAL FAILURE

Alternative term to wrong side failure.





TERM DEFINITION

SAFETY INTEGRITY (SI) The probability of a safety-related system satisfactorily performing the required functions under all the stated conditions within a stated period of time. (source: IEC 1508)

SAFETY INTEGRITY LEVEL (SIL))

One of four possible discrete levels for specifying the safety integrity requirements of the safety functions to be allocated to the safety-related systems. Safety Integrity Level 4 has the highest level of safety integrity; Safety Integrity Level 1 has the lowest. Safety Integrity Level 0 is non-safety-related. (source: IEC 1508 augmented)

SAFETY-CRITICAL Carries direct responsibility for safety. (source: ENV50129)

SAFETY-CRITICAL FAILURE

See wrong side failure.

SAFETY-RELATED Carries responsibility for safety (direct or indirect). (source: ENV50129)

SCHEME PLAN A longitudinally scaled layout plan, based on the record signalling plan, that is produced to depict proposed new or altered signalling systems.

SECTION ORDER An obsolete term, see level crossing order.

SECURE POWER SUPPLY A power supply system that can be relied upon to keep certain safety-critical signalling functions operating for a predetermined minimum time, in the event of a total failure of the main incoming supply.

Also known as guaranteed power supply.

SECURITY COPY The duplicate of a master record provided as a substitute when a master record is not available at its normal location.

SENSITIVE RELAY Generally a neutral relay with a high coil resistance and low power consumption. It may be used to give accurate timings in conjunction with a capacitor / resistor unit.

SERIAL (data link) A means of data transmission by which many discrete bits of information are encoded and sent in turn along a data link

SERIES BONDING The fail-safe method of bonding track circuits with rail sections connected in series, such that the failure of a single jumper cable, fishplate bond, or IRJ results in de-energisation of the track circuit.

SHEATH (cable) An outer protective layer of a cable containing the insulated conductor(s).

SHORT CIRCUIT BOND A jumper cable between the rails immediately beyond the final track circuit IRJs, in order to detect double joint failure. This is the only bonding required on non-track circuited lines in non-electrified areas.

SIGNAL BOX CONTROL AREA

See control area.

SIGNAL BOX NOTES A list of the key features of a signal box, or control centre, including any functions that are not clear from the signalling / scheme plan.

SIGNAL RAIL Non-preferred term; see insulated rail.

SIGNAL SIGHTING FORM A form that depicts the profile, location and other details of each signal as agreed by the signal sighting committee.

SIGNAL SPACING PARAMETERS

A tabular representation of the parameters (such as braking distances and average gradients) that may influence the relative positioning of signals.

SIGNALLER’S AREA The area of railway controlled or supervised by any one signaller, as defined by the boundaries between control panel sections or signalling workstations.

Formerly known as signalman’s area.

SIGNALLER’S ROUTE LIST A list of all point ends and releases between the entrance and exit signals of a signalled route, showing the position to which each is required to be set. Route lists are employed by the signaller when any power operated points are to be operated manually, or when the points in route setting systems are to be set by the individual point controls.

Formerly known as signalman’s route list.

SIGNALLING FUNCTION Final discrete component of a signalling system listed on control tables with a unique identity (such as signals, points, train detection devices, releases and level crossing barriers) and the circuitry or logic by which it is controlled an / or proved.


Signalling Design:

Production Guidance



TERM DEFINITION

Signalling functions are allocated (as defined by the control tables) to a specific interlocking controlled by a particular signal box (or other control point) and are given a unique identity within a particular signaller’s area.

SIGNALLING PLAN A longitudinally scaled layout plan defining a signal box control area and showing the signalling functions allocated to the signal box with their identities. Where applicable, it is extended to include the data collection area.

This plan is generally a derivative of the scheme plan.

SIGNALLING SYSTEM Equipment, circuitry and software associated with:

• lineside signals; • point operation; • level crossings; • train detection; • trainborne equipment conveying information about the state of the line; • operational telecommunications (excluding electrification control systems and

electrification telephones); and • fixed trackside safety systems.

SIGNALLING WORKSTATION

A workstation controlled by a signalling display sub-system with facilities for signalling control by trackerball and keyboard together with signalling display monitors and a general purpose VDU.

SIGNALMAN’S AREA Obsolete term, see signaller’s area.

SIGNALMAN’S ROUTE LIST

Obsolete term, see signaller’s route list.

SIGNIFICANT FAILURE A wrong side failure which by its seriousness or because of its volume introduces a risk requiring attention.

SINGLE RAIL Non-preferred term; see common rail.

SINGLE RAIL (SR) BONDING CONFIGURATION

A track circuit arrangement where only one rail (the insulated rail) is used with IRJs to separate the track circuits. The other rail (the common rail) is electrically continuous and is used for traction return purposes.

SINGLE RAIL (SR) BONDING CONFIGURATION

A jointed track circuit with IRJs in only one rail (the insulated rail) that is series bonded (except for the presence of spurs of limited length at Switches and Crossings). The other rail, known as the common rail, is electrically common to one or more adjacent track circuits.

SLEEPER An item of wood, steel or concrete of standard dimensions, used to support and gauge the track. (See bearer and timber.)

SLOW ACTING RELAY A relay in which both operation and release are intentionally delayed.

SLOW TO OPERATE RELAY

A relay in which the operation is intentionally delayed and the operate time is significantly longer than the release time.

SLOW TO RELEASE RELAY

A relay in which the release is intentionally delayed and the release time is significantly longer than the operate time.

SOURCE RECORD (signalling)

The signalling design record that does not bear the certification and from which the medium for production is derived. Examples are a negative or CAD file.

See also master record.

SPARE Equipment not connected to any part of the infrastructure. See also out of use.

SPUR (track circuit) A section of running rail required to be electrically common to a series bonded rail, but which is not itself in series.

STAGGER (electrical) The phase or polarity difference between one track circuit and the next, or between the rails on either side of an IRJ within one track circuit.

STAGGER (physical) Occurs where two IRJs in a pair of rails are not exactly opposite each other, thus creating a dead section between track circuits or within a track circuit.

STANDARD ROUTE INDICATOR (SI)

An alphanumeric route indicator having category two (medium range) performance (equivalent to the former theatre type route indicator).





TERM DEFINITION

STANDBY The state of an item when it is available but not required to be operating. (source: BS 4778)

STATE (of a function) Position or action of the equipment. Examples of complementary states are: operated / released, normal / reverse, on / off, raised / lowered, locked / free, enabled / inhibited, energised / de-energised.

In data driven systems this is stored as variable data.

STATE (of the infrastructure)

Configuration of an installation.

STATUS RECORD INDEX SHEET (software)

A list of design details and their versions for the configuration control of software (including ISSR and CISR for SSI systems).

STOCK RAIL See figure under switches and crossings.

STRUCTURE BOND A bond required in A.C. Electrified Areas, that connects adjacent lineside metal structures to the traction return rail system, where required to ensure staff safety through equipotential zoning.

SUPERVISED (level crossing)

Checked by visual observation, either directly or by use of CCTV.

SUPERVISORY (circuit) Control or indication circuit, particularly in respect of electric traction power supplies.

SWITCH NOMENCLATURE PLATE

See lever (or switch) nomenclature plate.

SWITCH RAIL See figure under switches and crossings.

SWITCH REINFORCING BOND

A jumper cable installed around the switch in S&C, in order to strengthen the fishplate bonds between the switch and crossing components and also to link two spur ends together, so improving the integrity of a parallel bonded rail section.

SWITCH TOE See figure under switches and crossings.

SWITCHES AND CROSSINGS (S&C)

Sections of track other than plain line. See the figure for constituent parts.

SYSTEM PROGRAM

The software necessary to drive a programmable electronic system.

Also known as fixed data.

Switch Toes Switch Rails Stock Rails

Heel Of Switch Rail

Closure Panels

Crossing Back

Check RailClosure Rails

Wing Rails

Crossing Angle

Crossing Nose


Signalling Design:

Production Guidance



TERM DEFINITION

SYSTEMATIC FAILURES Failures due to errors (including mistakes or acts of omission) in any safety life-cycle activity which cause it to fail under some particular combination of inputs or under some particular environmental condition. Systematic failures could arise in any safety life-cycle phase.

Examples of systematic failure include:

• Systematic failures due to errors in the safety requirements specification; • Systematic failures due to errors in the design, manufacture, installation, operation

of the hardware; • Systematic failures due to errors in the design, implementation etc. of the software.

(source: IEC 1508)

SYSTEMS APPROVAL Approval granted to systems.

TABLE OF SIGNAL ROUTES A comprehensive list of signal routes. They may either be shown on, or accompany copies of, the signalling / scheme plan.

TAIL CABLE A cable between trackside or on-track signalling equipment and other such equipment or a lineside apparatus housing.

For track circuits, see also track cable.

TECHNICIAN’S TERMINAL See maintainer’s terminal.

TEMPORARY WORK Alterations which remain in use for a limited period of time.

TERMINAL LINE The length of plain line approaching buffer stops. Single rail traction return is adequate for the final 300m of such lines in d.c. electrified areas, as traction return current is low.

TEST PANEL A control panel provided at the interlocking for testing or maintenance purposes. It may be provided temporarily for a commissioning or the function may be performed by the local panel.

TESTER IN CHARGE (TIC) Signalling engineer responsible for the testing and commissioning of new and altered signalling systems.

THROUGH CIRCUIT An external circuit drawn in entirety from supply to destination.

TIMBER An item of wood of non-standard dimensions, used to support the track in S&C areas. (See also bearer and sleeper.)

TIME DIVISION MULTIPLEX (TDM)

A non-safety-critical serial data transmission system that addresses each channel in turn and converts it into a unique digital code. It is generally used to transmit operating controls and indications between a signal box and interlockings.

TIME ELEMENT RELAY A relay, whose timing contacts do not change state until a predetermined time after operation or release, as appropriate.

Commonly known as timer.

TIMER See time element relay.

TOLERABLE (risk) Associated with a risk that is within the limits of upper and lower tolerability, as defined in Railtrack’s Railway Safety Case.

TOUCH POTENTIAL The potential difference between a person’s hand which is touching an exposed-conductive-part and any other part of the body which is touching another exposed-conductive-part at a different potential.

TRACK CABLE A track circuit tail cable which connects directly to the rails.

TRACK CIRCUIT ACTUATOR (TCA)

Non-preferred term, see track circuit assister.

TRACK CIRCUIT ACTUATOR INTERFERENCE DETECTOR (TCAID)

Non-preferred term, see track circuit assister interference detector.

TRACK CIRCUIT ASSISTER (TCA)

A device fitted to a vehicle which cause a 165kHz signal to pass between the wheels of the vehicle and assists in the breakdown of the insulation at the wheel to rail interface due to leaf-fall, rust etc.





TRACK CIRCUIT ASSISTER INTERFERENCE DETECTOR (TCAID)

A device fitted to the track which, when it detects the presence of a 165kHz signal in the rail, causes the track circuit to show occupied.

TRACK CIRCUIT BONDING The connection of one rail or component of a track circuit to another rail or component, so as to ensure electrical continuity. On rails carrying traction return current its function is performed by the traction return bonding.

TRACK CIRCUIT INTERRUPTER

A device that records the passage of a vehicle by causing a permanent disconnection within the track circuit until the device has been renewed.

TRACK JUMPING Occurs when a fast moving vehicle passes over a very short track circuit (or a short arm of a longer track circuit) and fails to de-energise the track relay.

TRACK RELAY (TR) Generally a neutral relay with a low coil resistance and low power consumption, which acts as part of a track circuit. It is either connected directly to the rails, or via a capacitor or tuner unit.

TRACKSIDE FUNCTIONAL MODULE (TFM)

SSI signal or points modules situated in lineside locations to operate and prove trackside equipment and interface with the data link from the interlocking via the data link module.

TRACTION BOND A cable specifically provided for continuity of traction return current, although it may additionally carry track circuit current.

TRACTION RAIL See common rail.

TRACTION RETURN BONDING The bonding required to carry the traction return current on both ac and dc electrified lines. Traction return bonding is generally parallel bonded.

TRANSMITTER (Tx) An electronic device that converts, modulates or encodes a discrete input, into a form that is suitable for sending to another site.

TRANSPOSITION BOND A jumper cable provided where track circuit polarities and / or traction return rails change sides across a pair of IRJs, or transposition joints. Purposes included the correction of track circuit polarity stagger or traction current imbalance, or to facilitate series bonding in S&C.

TRANSPOSITION JOINT An IRJ where transposition bonds are used to transpose the traction and / or track circuit rails.

TRAP POINT A point (usually switch and tiebar only), inserted in sidings etc., to unauthorised movements away from a running line.

TRIPLE-POLE (lamp) A double-filament lamp in which one end of each filament is connected to the cap shell and the other ends of the filaments are connected one to each contact plate. (source: BS 469)

TUNGSTEN HALOGEN LAMP A lamp in which the tungsten filament is enclosed in a gas filled quartz bulb containing a quantity of a halogen.

TWIN RELAY A unit which contains two electrically and mechanically independent relays.

TYPE APPROVAL Approval granted to an individual product.

UNDER VOLTAGE DETECTOR A permanent device, wired to the busbars, to inhibit operation and / or give an alarm to alert the maintainer, when the voltage falls below an acceptable level.

Also known as low voltage alarm.

UNINTERRUPTIBLE POWER SUPPLY (UPS)

A power supply with a secondary source which is capable of providing an uninterrupted changeover in the event of a failure of the incoming supply. It generally consists of low maintenance cells, a charger, voltage regulator, and monitoring, changeover and bypass devices.

UNRESOLVED (failure) At the time of closure, exhaustive testing has failed to reveal the fault but the possibility of a fault has not been totally eliminated.

UPDATE The process of revising the source document in accordance with the commissioning of Alterations, Amendments or modifications to design details.

VALIDATION Confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use have been fulfilled. (source: IEC 1508)

VARIABLE DATA Information associated with a data-driven system which records the real-time state of


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signalling functions.

VERIFICATION Confirmation by examination and provision of objective evidence that the specified requirements have been fulfilled. (source: IEC 1508)

VERSION CONTROL See configuration control.

VISUAL DISPLAY UNIT (VDU) MAP LAYOUT

A full size layout plan that details the information to be displayed for each screen overview or detailed view on a VDU.

VOLTAGE, NOMINAL Voltage by which an installation (or part of an installation) is designated. The following ranges of nominal voltage (r.m.s. values for a.c.) are defined:

• Extra-low. Generally not exceeding 50V a.c. or 120V ripple-free d.c., whether between conductors or to earth;

• Low. Generally exceeding extra-low voltage but not exceeding 1,000V a.c. or 1,500 d.c. between conductors, or 600V a.c. or 900V d.c. between conductors and earth. (source: BS7671 amended)

WHOLE-LIFE COST See life-cycle cost.

WING RAIL See figure under switches and crossings.

WRONG SIDE FAILURE A Failure which results in the protection normally provided by the signalling system being reduced.

Also known as safety-critical failure.

YELLOW BOND A jumper cable that is necessary to ensure the electrical integrity of a track circuit that is fully or partially parallel bonded. It is marked yellow to draw attention to its importance and to aid inspection.





4 Design Process An overview chart of the design process is given in Figure B1, divided into scheme phases and activities.

Guidance on each activity is provided in the various parts of this Code of Practice. Each is referenced accordingly on the chart.

The mandatory requirements are referenced to the relevant sections of GK/RT0201 and other standards.

Where the guidance given in this Code of Practice is not used, equivalent procedures should be followed that give the same level of safety integrity, are capable of being audited and have been agreed with the Infrastructure Controller.

5 Design Documentation and

Content The documentation associated with each scheme phase is shown in Figure B1.

Guidance on the minimum design requirements to be incorporated into each document is given in Part N.

Guidance on the technical content of design is given in the various part of GK/RC0706.

Figure B2 references the sections of Part M (presentation) and Part N(content) and the parts of GK/RC0706 relevant to each signalling sub-system. The mandatory signalling principles and design standards are also quoted.

The typical drawings shown in this Code of Practice are based on the signalling layout given in Figure R12, which is placed at the end of this Code of Practice for easy reference.


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Scheme Phases Scheme Status / Activity Feedback References Documentation

GK/RT0201 Section 10

GK/RC0701 Part G

GK/RT0201

Sect’n

GK/RC0701 Part

GK/RT0201 Sections 13 & 15 GK/RC0701 Parts K, M & N

client requirements set 6.1 Client Remit

CONCEPTION feasibility ascertained GK/RT0110 Outline Project Specification

project specified 6 Q Health & Safety File

risks assessed 17 R Health & Safety Plan

operating review held F

approved in principle 9.3 Scheme Plan

DEVELOPMENT site surveyed / assessed GK/RT0116

design specified 6.5 C Design Spec. and

systems & equipment approved GK/RT0104 Equipment Specs.

records handed over GK/RT0103

infrastructure correlated GK/RT0115

records corrected 6.7 Production

DESIGN detailed design produced 7 D Control Tables

design checked / verified 7.3 E and

approved for construction / accepted 9.6 Engineering

design certified and issued 11 H Details

CONSTRUCTION works constructed / verified

closure list issued 13.4 K

COMMISSIONING works tested / validated GK/RT0221

taken into service 9.7.4

updated final records handed back 12 J Design Records

statutory inspection / approval 9.7 including

IN SERVICE operation and maintenance 18 P Operation and

assets managed GK/RT0170 Maintenance

DE- 19 Manuals

COMMISSIONING

Figure B1 Signalling Scheme Overview Chart





Reference Reference GK/RC0701 Mandatory Standards

GK/RC 0706

Signalling System / Sub-System

Documentation Part M Presentation

Part N Content

GK/RT0002 Part B Signalling System Scheme Plan 3 1.1 GK/RT0004 Overview Signalling Plan 3 1.2 GK/RT0005 Stage Scheme Plans 3 1.8 GK/RT0007 Explanation or Reference Sheet 5.6, 6.1, 7 4.11.2 GK/RT0010 Operating Notice Diagrams 3 5.5 GK/RT0206 Safety Diagrams 3 5.6

Part C Power Supplies Power Distribution Plans 6.2 4.7 Power Cubicle/Rack Layouts 4.11.7 Power Supply and Earthing Arrangements 4.11.8 Location Circuit Dgms: Power Supplies & Busbar Analysis 8 4.12.3

GK/RT0205 Part D Electrical Circuits Signal Box and Interlocking Circuit Diagrams 5, 6, 7 4.11 GK/RT0330 Fuse Analysis 8 4.11.9

Contact Analysis 5.2, 8 4.11.11 Fusing and Looping Arrangements 6.1 4.11.19 Lineside Location Circuit Diagrams 5, 6.3 4.12 Location Circuit Diagrams: Miscellaneous Circuits 5, 6.3 4.12.7 Location Circuit Diagrams: Analysis 6.4, 8 4.12.8

GK/RT0009 Part F Interlocking Numbering Grids 1.4 GK/RT0039 Table of Signal Routes 1.7 GK/RT0060 Control Tables 4 3 GK/RT0061 Mechanical Locking Charts and Lever Details 4.8 GK/RT0063 Mechanical Operation Details 4.9 GK/RT0078 Electronic System Schematic and Allocation 5.3 4.11.5

Lever Lock and Circuit Controller Analysis 8 4.11.10 GK/RT0202 Temporary Approach Control and Route Dis Link Analysis 8 4.11.14

Interlocking, Control and Associated Circuits 5 4.11.16 Alarm and Indication Circuits 5 4.11.17 Maintainer's Monitoring Panel Circuits 5 4.11.20 Electronic System Details 4.13 Part G Apparatus Housing Location Area Plans 3 4.1 Equipment Room Layout 4.11.3 Equipment Rack Layouts 7 4.11.4 Location Circuit Diagrams: Frontsheet 3 4.12.1 Location Circuit Diagrams: Case or Equipment Room

Layout 7 4.12.2

GK/RT0105 Part J Transmission Cable Route Plan 4.4 Systems and Cable Schematic Plans 6.2 4.5 Cabling Cable Core Plans 5.2, 6.2 4.6 Inter-Rack/Cubicle Cable Schematic Analysis 5.2, 8 4.11.6 Cable Termination Rack Layout 6.4 4.11.12 Cable Termination Analysis 5.2, 6.4, 6.5,

8 4.11.13

System Schematics (external) 5.3 4.11.22 0041 to 0054 Part K Block Working GK/RT0025 Part L Signalling Control Signal Box Notes and General Notes 1.3 GK/RT0026 and Display System Signalling Control and Display System Circuits 5 4.11.18 GK/RT0027 Signalling Control and Display System Details 5.1

Isolation Overlays 5.3 Signaller’s Route Lists 5.4 Part M Train Describer Remote Control and Train Describer Interface Circuits 5 4.11.15 Train Describer System Details 4.13.4 Part N Telecommunication

s

GK/RT0062 Part P Points Soleplate or S&C Plans 4.3 GK/RT0065 Mechanical Engineering Details for Points and Signals 4.10

Location Circuit Diagrams: Point Circuits 5, 6.3 4.12.6 GK/RT0040 Part R Cab Signalling

Part S Lineside Signals Signal Spacing Parameters 1.5 (including Train Aspect Sequence Charts 1.6

GK/RT0031 Interactive Systems) Signal Sighting Forms 1.9 to 0038 Location Circuit Diagrams: Signal Circuits 5, 6.3 4.12.5

GK/RT0011 Part T Train Detection Track Section Schedule 3.4 GK/RT0251 Bonding Plans 4.2 GK/RT0252 Location Circuit Diagrams: Train Detection Circuits 5, 6.3 4.12.4 GK/RT0070 Part X Level Crossings Level Crossing Ground Plan 2

Level Crossing Schematics 4.11.21 0029 & 0030 Part Y Protection Systems Lockout Device Diagram 3 5.2

Figure B2 Design Content of Signalling Sub-Systems References


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Part C Design Specification Guidelines

I Production Method A draft specification should be prepared in which all of the topics contained within the following guidelines are considered for inclusion if their application is appropriate to the signalling scheme.

To enable the specification to be recognised within a standard format there may be benefit in providing all headings in every specification and endorsing 'N/A' those which are not applicable. In this way omissions due to errors of judgement at the draft stage are less likely to occur.

The draft specification should be ratified by holding a review meeting, chaired by the responsible design engineer, with attendance by representatives from each discipline, function or sub-contractor involved. Each representative should be able to discuss any item relating to the party which they represent. The meeting should be held at the earliest opportunity, and the specification should be based on an approved scheme plan.

Care should be taken to ensure that the meeting is constrained within the scope of the client remit and outline project specification (OPS). Any attempts to change the scope of the project should be treated as a change subject to change control.

2 Acceptance After the draft specification has been updated to agree with the proceedings of the meeting, it should be signed by the responsible design engineer, and accepted by Railtrack. Procedures should be in place to define the Acceptance responsibilities, which should generally involve both operational and infrastructure concerns.

3 Format The content of the design specification should enable the client's requirements, in terms of train operations and dependability (see Part P), to be met.

The scheme should be considered under the following headings:

3.1 Outline and Scope A brief description of the agreed scheme should be provided, as defined by the client remit OPS and the scheme plan and the extent of works.

Where existing signalling is being altered, the existing arrangements should be described with a statement of what it is proposed to retain. New, retained and abolished signal boxes or other control points should be stated.

Reference should be made to the standards to which the works are to be designed, as listed on the scheme plan or certificate of compliance (see Figure Cl).





Certificate of Compliance

Name of Project / SIgnalling Scheme I certify that the signalling design produced for the above project has been produced, independently checked and approved by competent persons.

Reasonable care and diligence has been exercised in the development of the design to ensure that

a) any risk assessment and design calculation has been correctly performed;

b) the resulting signalling system and equipment, if constructed as designed, will be capable of meeting the client's specifieded requirements; and

c) the design conforms to the signalling principles and standards listed below:

[a typical list is given in Figure 52; the version of each should also be quoted]

The design also conforms to; I) Health and Safety Legislation; ii) HMRI Railway Safety Principles and Guidance; iii) British and European Standards; iv) Railway Group Standards; v) Railtrack Line Standards; and vi) other relevant regulations and standard's, current at the time of scheme plan approval. apart from the exceptions listed below;

(specific temporary non-compliances, etc. should be listed here] Signed ............................................................................. Date ..............................

Responsible Design Engineer

Figure Cl Typical Certificate of Compliance

3.2 Timescales A bar chart should be provided, showing proposed dates for the key milestones appropriate to each alteration or stage (defined in the stagework programme).

This should feature most of the activities listed in Figure B1, in particular dates closure lists are to be issued and final records handed back.

3.3 System Safety Assurance The different means to be used to assure safety should be stated (and the interfaces in a hybrid approach) in accordance with GK/RT0206. A statement of the level of safety to be provided by the signalling system should be included.

This may include risk assessment, together with any mitigation or control measures arising, or functional safety analysis. Any decisions based on risk Assessment should be stated.

Reference should be made to any risk assessment reports or safety cases. See Part R for further guidance.

3.4 Occupational Safety Special risks that might arise during the execution of the works must be stated in health and safety documentation, in accordance with GK/RT0201.

Reference should be made to the health and safety plan. See Part Q for further guidance.

3.5 Systems and Equipment Any safety cases or type approval required for new systems or equipment in accordance with GK/RT0l04, should be stated, or evidence of historical operating experience referenced.


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Consideration should also be given to the spares availability with regard to providing a design which can be supported throughout the life of the installation. The strategic spares to be provided with the project should be those required on standby during commissioning. Long lead times for equipment delivery should be highlighted.

3.6 Previous Design Specifications Any relevant information should be extracted from the design specification of the existing installation.

3.7 Competent Resources Resources required or allocated to undertake design should be stated, including sub-contract elements, where appropriate.

All resourced personnel should be competent for the allocated task.

3.8 Management of Interfaces Relationships between design authorities should be stated, as well as interfaces with other authorities, disciplines, functions and sub-contractors described in GK/RT020l.

The interfaces with the construction, testing, telecommunicion, procurement and manufacturing functions should be defined; also with the permanent way, electric traction, power supply and property disciplines; as well as with train and signalling operations.

Information and drawings required to be passed between parties, e.g. scheme plans, bonding plans, S&C plans, power supply schematics, level crossing ground plans and stagework details (see Part N), with agreed dates, should be identified and the interdisciplinary checks required should be defined.

Design authorities should have procedures in place where necessary to control the internal interfaces with other signalling functions and sub-contractors. Railtrack should have procedures in place where necessary to control the external interfaces between disciplines.

3.9 Correlation The extent of correlation required should be stated, together with any responsibilities for subsequent updating and remedial action.

It should be confirmed that the condition of wiring will not impede correlation, or otherwise give alternative measures proposed.

3.10 Assessment of Existing Signalling Any factors identified in an Assessment of the proposed works, in accordance with GK/RT0116, should be listed, together with a statement of the condition of the existing infrastructure.

Any refurbishment required for equipment or housings being retained should be stated.

Special risks that might arise during the execution of the works must be stated in health and safety documentation, in accordance with Section 3.4.

It should be stated that redundant assets are to be recovered in full, unless the condition of the existing infrastructure and the temporary nature of the work make other arrangements desirable (see Part L).

Any outstanding surveys, e.g. for signal sighting, level crossings, cable routes, apparatus housings or track circuit clearances, should be stated.

Where necessary, e.g. for surveying level crossings, Railtrack should supply to the design authority all known details of buried services and land boundaries.





3.11 Stagework and Testing Strategies The testing and stagework strategies should be developed from the OPS. The methods of changeover should be stated, and, where stagework is necessary, whether the stages require sub-dividing into individual packages of work, i.e. as separate alterations.

The design should facilitate the testing activity and ensure testability. Any special testing facilities, such as the provision of a test panel, should be identified.

The overall commissioning should be staged as necessary to facilitate the safety of the construction activity and changeover. A stagework programme should clearly identify all staged commissionings proposed.

The means of staging complex systems and interfaces should be carefully considered. For partial commissioning arrangements see Part L. Technical solutions include:

• commissioning the final electronic interlocking and inhibiting routes not yet available;

• installing insulated rail joints and bonding around until required; • “top-nutting” temporary stagework cables from the old interlocking onto

outgoing cables at the new interlocking, with the internal links open; and • converting signals, points, and / or track circuits to operate via the final tail

cables.

3.12 Environmental Considerations Any harsh or unusual operating environments and hazardous working environments should be stated. The policy for the protection of the environment should be referenced.

The operating environment should include electromagnetic compatibility (EMC) considerations (such as equipment proximity), climatic, corrosive, or explosive conditions, considering the likelihood and impact of hazards, such as flooding or sea water spray and the degree of dust and water protection required. Any requirements for zero-halogen low-smoke (ZHLS) cables (e.g. in sub-surface stations) or double sheathed internal wiring (e.g. in metal trunking) should be specified. Any special measures to allow use outside the manufacturer’s approved environment should be stated. Areas where the infrastructure controller requires special provision against vandalism should be listed, together with the measures proposed.

The working environment should consider noise, vibration, dust, or other factors, such as treatment, cutting or drilling likely to generate hazardous fumes or dust. Hazards likely to be experienced by installers, maintainers, or operators, and the necessary protective measures to be taken, must be stated in health and safety documentation, in accordance with GK/RT0201. This includes the handling of hazardous substances (e.g. batteries). See also Part Q.

Noise and other environmental nuisance should also be considered, in particular to minimise emissions and reduce waste, taking into account the life-cycle environmental impact of products and services.

Note that premises (including relocatable premises that remain occupied for a period exceeding six months) are required to be registered with the local authorities. Planning permission may be required. Further details are given in GK/RC0706, Part G.


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3.13 Operating Requirements The client’s train operating requirements should be stated. Items that require special consideration at a review meeting are listed in Part F.

Other design parameters and assumptions made, such as permissible speeds, headway, type of electric traction, etc, should be stated. See Part N for the assumptions used in scheme plan development.

3.14 Dependability The client’s dependability performance should be specified. Guidance in satisfying them is given in Part P.

Design features that assist preventative and corrective maintenance should be considered in conjunction with the future maintenance policy.

3.15 Design Production Methodology It should be stated that all design details are to be produced in accordance with GK/RH0710. (Details of the process are given in Part D.)

Special production requirements should be identified, including:

• arrangements for record updating and any redrawing necessary; • the predominant method of production for each alteration (the ‘one drawing’

method is preferred for relatively simple alterations, whilst the ‘two drawing’ method is preferred for complex alterations on a large scale, like-for-like renewals and temporary work);

• any proposal to mix different methods of production; • the scope and type of analysis provision (when undertaking alterations at an

installation without full analysis); • the scope of provision of other drawings or information missing from the

installation (see Part N); • the number of sets of design detail for distribution and their format; • the need to produce new drawings at a size which is compatible with existing

non-standard sizes; • any requirement to use imperial dimensions, rather than metric; and • the requirements for operation and maintenance manuals for propriety

equipment.

3.16 Overlapping and Parallel Work Any requirement for overlapping or parallel design should be stated, with the necessary control measures, in accordance with GK/RT0201.

3.17 Special Control Measures Any special control measures should be stated or relaxations granted for the special cases described in Part L, such as whether all previously designed works have been commissioned, and, if not, the means of controlling any discrepancies arising.

3.18 Check Recording The design check recording methodology to be used should be stated, as described in Part E.

3.19 Configuration Control The means of applying configuration control, particularly to software systems, should be stated, as described in Part K.

3.20 Approval Documentation Responsibilities for collating documentation to be submitted for Railtrack project approval and statutory approval should be stated (see GK/RT0201).

2.21 System Interfaces System interfaces or compatibility that present particular hazards should be defined and control measures proposed, in accordance with GK/RT0206.





Scheme fringes and method of interfacing with existing signalling systems should be particularly considered.

3.22 Engineering Input Sufficient information is required to enable the control tables and engineering details to be compiled from the scheme plan.

The content of the design should be in accordance with the standards referenced (see Section 3.1).

However, any special engineering requirements should be specified, particularly any decisions made regarding types of systems or equipment, or the provision of special facilities or drawings. Each applicable sub-system from Figure B2 should be considered in turn.

Any special equipment for unusual environmental conditions (see Section 3.12) should be identified.

Particular consideration should be given to the client’s operating (see Section 3.13) and dependability (see Section 3.14) requirements.

Examples of engineering choices include:

a) Overview: type of signalling system, location and type of control point(s) and interlocking(s) (GK/RC0706, Part F);

b) Power supplies: estimated total loads, provision for standby supplies, duplication of equipment and type of protection from indirect contact to be provided, e.g. earthing, (GK/RC0706, Part C);

c) Circuits: type(s) of electric traction/power lines to be immunised against (GK/RC0706, Part D);

d) Interlockings: diversity, or other means of achieving availability, facilities for maintainers, proposed relaxations, (GK/RC0706 Part F), particular operating features considered in Part F, Section 2;

e) Apparatus Cases: whether lighting is required (Part N, Section 4.12.7), whether disconnection boxes should be provided for tail cables and whether relocatable equipment buildings (REBs) are preferred (GK/RC0706, Part G);

f) Cabling: whether diverse routing is required and any special types of cable route or undertrack crossings necessary (Part N, Section 4.4);

g) Signalling Control and Display Systems: type of system and interface with the interlocking(s) (GK/RC0706, Part L), the form in which Signaller’s Route Lists should be provided (Part N, Section 5.4) and any fixed ground frame diagrams required for operators (Part N, Section 5.1);

h) Telecommunications: any signalling requirement in telecommunication transmission systems (GK/RC0706, Part J), type of signaller’s interface and any special telephones or radio systems required (GK/RC0706, Part N);

i) Points: type of operation, any long timbers or gapped conductor rails and point switch heating arrangements (GK/RC0706, Part P);

j) Signals and Indicators: type of train interactive warning system required and whether route indicators and / or position light signals should be fibre optic (GK/RC0706, Part S);

k) Train Detection: type and immunity, axle counter option, whether duplicate tail cables, yellow bonding (GK/RC0706, Part T) or track section schedules are required (Part N, Section 3.4) and how track circuits should be depicted on bonding plans (Part N, Section 4.2.2); and


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l) Level Crossings: types of protection (and CCTV transmission systems, where applicable), whether statutory orders are required (GK/RC0706, Part X) and whether schematic drawings are required (Part N, Section 4.11.21).

3.23 Change Control The method of controlling and authorising changes to the project, including changes to the client’s requirements, scheme plan and design specification, etc, should be stated.

A log of significant changes or variations to the scheme must be appended to the design specification, in accordance with GK/RT0201. “Significant” change should be defined here.

4 Review and Changes The design authority should establish and maintain an effective design review procedure. The design specification is a key reference document during the design review process.

The objectives of the design review are to establish that:

a) the design option chosen is feasible and fit for purpose; b) the design of the signalling system will meet all the dependability criteria; c) the system being designed can be produced, checked, constructed, tested,

commissioned, operated and maintained; d) adequate documents exist to define the design and associated activities listed

in item (c); e) all interface issues have been addressed; and f) all regulatory and safety requirements have been considered.

Design reviews should cover all quality-related factors, and comprehensive check lists should be compiled and used for each review.

See Part F for the operating requirements review.

Once a design specification has received formal acceptance signatures, any changes required should be managed under an agreed control process (see Section 3.23).


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Part D Design Record and Production Control

I Design Media The relationship between the source record, master record and associated media is given in Figure Dl. They can take the form of a computer aided design (CAD) design file, some electronic data medium, or a negative.

Media:

Technique SOURCE RECORD

Medium for Production

MASTER RECORD (Medium for Obtaining

Record Prints)

CAD

Design File Production Copy

of Design File Verified to Master

Signed Print of Design File

DATA

Two Master Disks/tapes

Production Copy of 1 Master Disk/Tape

Verified to Other

Signed Data Listings

NEGATIVE Negative (or Security Copy)

Negative Signed Print of Negative

Figure DI Design Media

1.1 Source Record There should be only one source record at any one time. It should depict the state of the current infrastructure. The source record should be unsigned so that it can be used to derive the medium for production. Except when alterations are in production (see Section 2), it should be retained by the records custodian.

It should take one of the following forms;

a) CAD: Design details are produced as design files on CAD workstations and records held in electronic or data storage medium.

b) Data: Data files are prepared on the hard disk of a workstation (the working disk). The data files that comprise the source record are held in the form of two identical write-protected copy disks or equivalent e.g. Master Disk (1) and Master Disk (2). Labels for these disks are illustrated in Figure K2.

c) Negative: This uses the media of pencil or ink on plastic film or linen. Its place should be taken by a security copy when the negative is used as the medium for production.

1.2 Medium for Production This is either the source record (i.e. where it is a negative), or a copy of the source record for production purposes.

It should take one of the following forms:

a) CAD: This should be a production copy of the design file verified to a copy of the signed master record by the design authority

b) Data: This should be a production copy of Master Disk (2) on the working disk and should be verified to Master Disk (1). Other electronic media may also be used in a similar manner

c) Negative: The negative itself should be used as the medium for production.





1.3 Master Record There should be only one master record, which should be provided on white paper and endorsed "Master Record'. It is the fully signed copy of the current source record, from which record prints are obtained. It is retained by the records custodian whilst it is current and can be used to verify the source record.

The master record endorsement should be applied in a manner to prevent it appearing on the duplicate copies (e.g. outside the drawing border, on the reverse side of the drawing, or by punching). (This also applies to security copies.)

It should take one of the following forms:

a) CAD: The CAD master record is a signed print of the current design file. CAD master record prints cannot, however, be used to reproduce design details which have to be plotted in colour (e.g. level crossing ground plans). All such copies should be individually plotted and verified.

b) Data: A signed data listing should be used as the master record.

c) Negative: The master record is a signed print of the negative.

1.4 Functional Data Media The appropriate system applications manual should be followed for the production of the functional data media, such as EPROMs (erasable programmable read only memory).

EPROMs may be obtained from the master data disks (or equivalent) or from the source data files, using an EPROM programmer. Two master EPROMs should generally be obtained in this way.

Production EPROMs, used in the signalling equipment, may be duplicated either from a master EPROM, from a master data disk (or equivalent), or from the source data files. They should be verified against a second master of some type.

2 Security Configuration control is considered in Part K.

A pictogram showing typical applications of source record control is given in Figure D2.


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Figure D2 Source Record Control Pictogram

Note: A B C continued on Figure D3

ARCHIVE

Copy NewMasterPrint

Colour PlotORPlot & Colour(Red work onlyfor Two Drawing Method)PRODUCTION RECORDS

& ColourGreen Work

Two DrawingMethod Only

ArchiveUpdated Design File

& Destroy OldFinal Update

Production Design File

Copy Source RecordDesign File

Copy MasterRecord Print

Alter / Update

A CB

Plan Room Secure Environment Destroy Master

Replace withNew Plot

Alterations inProgress

New SourceRecord

ARCHIVE

Plot UpdatedDesign File

CommissioningDay

(a) Computer Aided Design

(b) Negatives

Alter Source Record

Update SourceRecord

PrintPrint&Colour(Red work onlyfor Two Drawing Method)PRODUCTION RECORDS

Print & ColourGreen Work

Two DrawingMethod Only

A CB

Plan Room Secure Environment Destroy Security Copy ReplaceSourceRecord

CommissioningDay

Print SecurityCopy

ReleaseSourceRecord

Alterationsin Progress





2.1 CAD When an alteration is commenced, the records custodian should endorse the CAD master record “Security Copy: Alterations in Progress”. A single copy of the design file is then permitted for altering and updating on the work station. This is known as the production design file. A separate security copy is not required.

When the alteration has been commissioned, and when the production design file has been updated for final records, a new master record should be plotted. The records custodian should place this in the secure environment and destroy the previous version. The old record design file should then be replaced by the newly updated production design file.

The records custodian should have procedures in place to ensure the integrity of software records.

2.2. Data When an alteration is commenced, the records custodian should identify the master disks (or equivalent) and the master data listing as “Security Copy: Alterations in Progress”. A copy, or copies, of the data files are then permitted for altering to the final arrangement on the workstation hard disk, in accordance with the appropriate system applications manual. These are known as the production data files.

When the alteration has been commissioned, a new master data listing should be plotted. The records custodian should place this in the secure environment and destroy the previous version. The old record master disks should be replaced by the new record master disks. A copy of the old master disks and EPROMs should be labelled “superseded” and archived. All old copies that are not archived should be erased or destroyed.

The records custodian should have procedures in place to ensure the integrity of software records.

2.3 Negative When the negative is released from its secure environment for altering and updating, the records custodian should replace it with a paper security copy, endorsed “Security Copy: Alterations in Progress”.

After the alteration has been commissioned and the negative updated for final records, a new master record should be plotted. The records custodian should place the negative in the secure environment and destroy the security copy. The old master record should then be replaced by the new print.

In the event of an alteration being cancelled, it may be necessary to either:

• restore the negative to its original state; or • create a new negative from the security copy and destroy the old negative.

3 Production and Record Copies

3.1 Production Office Copy The production office copy is a print of the altered source record (CAD production design file, production data files or negative) from which the production issue copies are obtained. The process is described in Section 4. It is printed on white paper, coloured, issue-dated and endorsed “Production Office Copy”.

There should be only one production office copy of each version of the source record, the latest version being defined by the appropriate approval and issues record (AIR) (see Part K).

3.1.1 Data Systems The production office copy may take the form of a data listing (showing the data altered to the final arrangement), or of a different list automatically generated by comparing old and new versions of master data disks, or equivalent.


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3.2 Production Issue Copies The following issue copies should be duplicates of the production office copy taken at the appropriate stage and should be identical in all respects, including colouring (except for copy identification):

a) Checking Copies: These copies are used solely for checking activities by the design authority (see Part E) and are endorsed “Checking Copy”.

b) Interdisciplinary Checking Copies: The design authority should have controlled documentary processes in place to enable the interdisciplinary checks defined in the design specification to be undertaken with the appropriate parties.

c) Approval Copies: Scheme plans issued to Railtrack for Approval in principle should bear an Approval and version panel (see Part K) and be endorsed “Railtrack Approval Copy”. Engineering details issued to Railtrack for Acceptance should be endorsed “Acceptance Copy”. Design details submitted to Her Majesty’s Railway Inspectorate (HMRI) for statutory scheme Approval should be endorsed “Statutory Approval Copy”. The Approval requirements are given in GK/RT0201.

d) Test Copies: Design details that are issued for testing purposes in accordance with GK/RT0221 should carry the prescribed testing grid. They should be printed on pink paper, or bear a pink label, and be endorsed “Test Copy”. Test copies should also display the name of the design authority to which they should be returned for record updating purposes, with provision for certification after being endorsed with all commissioning modifications. For closure lists see Part K.

e) Construction Copies: Construction and works engineer’s copies should be printed on white paper and endorsed “Construction Copy” and “Construction Management Copy” respectively.

f) Other Copies: As listed in the design specification.

3.3 Record Issue Copies The following issue copies should be duplicates of the master record, printed on white paper and be identical in all respects (except for copy identification):

a) Correlation Copies: Design details that are issued for correlation purposes in accordance with GK/RT0115 should be endorsed “Correlation Copy”. They should also display the name of the authority to which they should be returned for record updating purposes, with provision for certification after being endorsed with all correlation corrections. Alternatively, they may be copies of the source record.

b) Maintenance Copies: Maintenance and maintenance engineer’s copies should be printed on white paper and endorsed “Maintenance Copy” and “Maintenance Management Copy” respectively. Maintenance copies may be annotated and certified with correlation corrections, commissioning modifications (see Part G) or non-conceptual design alterations (see Part L), provided the resulting temporary maintenance copy is replaced with a final record copy within an appropriate timescale. The requirements for maintenance records are given in GK/RT0201.

c) Other Copies: As listed in the design specification.

4 Production Processes The predominant method of production for each project should be agreed in the design specification. The “One Drawing” method is preferred for relatively simple Alterations, whilst the “Two Drawing” method is preferred for complex alterations on a large scale, like-for-like renewals and temporary work.

Where any other process is used this should be documented clearly in the design specification.





A pictogram showing typical production processes is given in Figure D3.

Production processes are dependent on which form of source record and which presentation method is in use. Processes that may be used for undertaking alterations to existing drawings are summarised as follows (omitting checking copies and procedures - see Part E):


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Figure D3 Production Process Pictogram





4.1 Computer Aided Design (CAD) 4.1.1 "One Drawing" Method a) Obtain a production copy of the archived record design file from the records

custodian for use on the workstation.

b) Records custodian endorses the CAD master record 'Alterations in Progress”.

c) Draft the design on a copy of the master record.

d) Superimpose the new requirements on the production design file.

e) Plot the altered design file for the production office copy with the new and redundant requirements shown in red and green.

f) Obtain duplicate copies for issue by colour plotting or by use of the colour copier.

g) Update the production design file to the final arrangement, removing redundant requirements.

h) Plot a new master record from the updated production design file.

i) Replacement prints, for maintenance records, are then obtained from the master record, using a plain paper copier

j) Supply updated design file and master record print to the records custodian, along with any superseded design details for deletion.

k) Records custodian places the new CAD master record in the secure environment and destroys the old one.

4.1.2 "Two Drawing" Method a) Obtain a production copy of the archived record design file from the records

custodian for use on the workstation.

b) Records custodian endorses the CAD master record 'Alterations in Progress".

c) Draft the design on a copy of the master record.

d) Alter the production design file to the final requirements.

e) Obtain a second copy of the old master record for the green production office copy and identify the redundant requirements in green or alternatively colour plot from the production design file (green and black levels).

f) Plot a new master record from the altered production design file.

g) Obtain the red production office copy with the new requirements shown in red, either by polling from the production design file (black and red levels), or by taking a copy of the new master record and hand colouring.

h) Obtain duplicate copies of both for issue by colour plotting or by use of the colour copier.

i) Replacement prints, for maintenance records, may be obtained immediately from the master record, using a plain paper copier.

j) Supply updated design file and master record print to the records custodian, along with any superseded design details for deletion.

k) Records custodian places the new CAD master record in the secure environment and destroys the old one.


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When the green production office copy is obtained from the signed master record, a certification block should be applied to incorporate the new version number, the initials of producer and checker and the date the source record is updated.

If subsequent alterations are carried out by manual methods then the design files held in CAD should be updated accordingly and the original master records replaced.

4.2 Data a) Obtain production copies of the data files from the records custodian for use

on the workstation hard disk.

b) Records custodian identifies the record master disk, or equivalent, (and master data listings) as “Alterations in Progress”.

c) Draft the data changes on a copy of the data listings.

d) Update the production data files to the final requirements.

e) Obtain a second copy of the old data listings for the green production office copy and identify the redundant requirements in green, or alternatively create a difference list printout by comparing the old and new data files.

f) Print out the new master data listings from the updated production data files.

g) Obtain the red production office copy by taking a copy of the new master data listings and, if required, colouring the new requirements in red.

h) Create the two record master disks (or equivalent) and program the new master EPROMs.

i) Obtain duplicate production EPROMs for issue to site.

j) Records custodian archives the updated master data disks (or equivalent) on commissioning and erases the old record master disk.

k) Records custodian places the new master data listings and master EPROMs in their secure environments and deletes the old ones.

4.3 Negatives 4.3.1 "One Drawing" Method a) Obtain the negative from the records custodian.

b) Records custodian replaces it with a security copy.

c) Draft the design on an additional print

d) Superimpose the new requirements on the negative (or production master print).

e) Obtain a print of the altered negative (or production master print) for the production office copy with the new and redundant requirements shown in red and green.

f) Obtain duplicate copies for issue by manual transcription or by use of the colour copier (preferred).

g) Update the negative to the final arrangement, removing redundant requirements.

h) Print a new master record from the updated negative.

i) Replacement prints, for maintenance records, are then obtained from the negative, either directly, or via the master record.





j) Return the negative and new master record to the records custodian on commissioning, along with any superseded design details for deletion.

k) Records custodian destroys the security copy and replaces the master record.

4.3.2 "Two Drawing" Method a) Obtain the negative from the records custodian.

b) Records custodian replaces it with a security copy

c) Draft the design on an additional print

d) Obtain another print of the negative for the green production office copy and identify the redundant requirements in green.

e) Alter the negative to the final requirements.

f) Obtain a print of the altered negative for the red production office copy with the new requirements shown in red.

g) Obtain duplicate copies of both for issue by manual transcription or by use of the colour copier (preferred).

h) Print a new master record from the updated negative.

i) Replacement prints, for maintenance records, are then obtained from the negative, either directly, or via the master record.

j) Return the negative and new master record to the records custodian on commissioning, along with any superseded design details for deletion.

k) Records custodian destroys the security copy and replaces the master record.


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Part E Verification Process

I Checking Overview This section details a suggested systematic independent checking process for design verification.

1.1 Design Process Design details for a typical scheme (see Part N) may be divided into consecutive groups, each of which is required to be produced, checked and, where applicable, approved before proceeding to the next group. Otherwise, the adoption of parallel processes, where permitted in GK/RT020I, may result in additional rework.

a) Outline project specification (OPS) and design specification.

b) Scheme plan, associated documentation for approval purposes and signal sighting notes derived from group (a).

c) Control tables derived from group (b).

d) Engineering details such as circuit diagrams, data, cabling and final ground plans derived from groups (b) and (c).

e) Operational and maintenance details derived from groups (b), (c) and (d).

1.2 Systematic Approach to the independent Check The checker is required to adopt a systematic, auditable approach such as given below:

1.2.1 Familiarisation The checker should:

a) obtain a checked copy of any design details from which those being checked have been derived;

b) examine the OPS and design specification, to establish the exact scope of the scheme and obtain the scheme parameters (see Part C);

c) inspect whichever of the contract documents are pertinent, and become familiar with local site information, the impact of adjacent or dependent work and other relevant correspondence;

d) refer to the appropriate pads of GK/RC0706 (see Figure B2); e) establish that any standards declared in the development process are still

applicable and valid; f) establish that the correlation process has been carried out and the records

updated, where applicable; g) establish that the producer has achieved the design objectives listed in

GK/RT0201and certified the design details; and h) consider the verification process features listed in GK/RT0201.

1.2.2 The Check This is specific to the relevant group of design details being checked (see Part N). The applicable parts of GK/RC0706 should be used to perform a systematic technical check.

The check should include all assumptions, interfaces, calculations, risk arguments and safety analysees.

1.2.3 Error Recording This process is described in Section 3.2. Any design details which are identified by the checker as requiring correction should be returned to the producer, together with a brief indication of the area where corrections are required, so as not to compromise the final design.





1.2.4 Completion The checker should re-check the corrections arising from the error report, sign and date it, take a final look through the design details and, when satisfied, sign them as checked.

1.3 Alterations to Existing Drawings Where design details are produced for a completely new signalling installation, a 100% check of all design details should be carried out. When using contacts of an existing relay, the relay circuit should be checked to ensure that all the expected controls are actually present in it, rather than placing any reliance on the relay name. When altering an existing relay circuit, the contact analysis for the relay should be used to ascertain the effect of the alteration on all the other circuits where contacts of the relay are used.

Where design details are produced for alterations to an existing signalling installation, a 100% check of the design details associated with the altered area should also be carried out (i.e. where part of a circuit is altered then the total circuit should be checked). Any circuits which are not altered need only be checked to ensure that theft principle of operation is consistent with the altered circuits.

1.4 Assistance and Environment It is often beneficial for two people to check, with the checker reading the plan, wiring diagrams or technical data, and an assistant ticking the control tables, locking tables or the relay contact analysis. Both should be certificated as competent in their respective duties.

Ideally the checking process should be carried out in an environment which is isolated from the general day to day activities of the design office. A room, ideally without telephones, should be identified for checking activities to minimise interruptions. The necessary dialogue of the checking process is not then disruptive to the general design office.

2 Design Tool Verification

Where the safety integrity level (SIL) of a drawing or data tool is less than the target SIL for the system under design, then a sufficient degree of verification should be provided to protect against any deficiency, such as faults caused by user error, or system error, or deficient maintenance. (Most commercially available tools have a SIL of zero.)

This is generally satisfied by checking the output, including any calculations, to first principles. Where the SIL warrants it, a sample check only may be sufficient. Any such relaxation should be justified by risk assessment (see Part R).

It may be necessary to apply these provisions in the following cases (this list is not exhaustive):

a) rulers (e.g. regular calibration checks); b) calculators (e.g. calculations checked using a different calculator); c) photocopiers and colour plotters (e.g. regular maintenance); d) fax machines (see Part S for a verification procedure); e) CAD systems and data systems (see Part D, Section 1.2 for verification

requirements before commencing design); f) EPROMs (see Part D, Section 1.4); g) data preparation software; h) word processors and spreadsheets used to generate design details, such as

control tables and signal spacing parameters, (see Part N); and


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Production Guidance



i) CAD standard cells, standard drawings and typical circuits (see References). These should be checked in full to first principles, unless they carry their own verification (and, where applicable, approval), are the current version and are to be used within their application criteria.

3 Check Recording Methodology

The checking and error reporting processes should be recorded in an auditable manner, as required by GK/RT0201. Tick marking and error recording and / or check records generally satisfy this requirement

3.1 Tick Marking The progress of the checking process should be recorded by a system of marking or ticking a checking copy. Every item should be ticked in a colour that will identify the checker (other than red, green or black). Other methods may be equally acceptable provided that all the same features are included and are demonstrably capable of independent audit procedures.

This process is also carried out by the producer prior to the checker commencing his check, either on a different copy or in a different colour on the same copy,

Tick marking may not be necessary when checking like-for-like transcriptions, colouring, or updating of records.

3.2 Error Recording During the checking process the checker should be required to record and categorise any errors found. This recording process is aimed at identifying individual errors and discernible error trends so that corrective measures may be applied. This may take the form of local methods to raise awareness levels, or formal training targeted either individually or collectively to rectify the areas of inexperience or deficiencies in knowledge levels. The aim is to identify errors, learn from the process so that errors are not repeated, share the experience through error review, and establish consistent check processes which may be tracked and audited.

A suggested procedure is as follows:

a) All errors found during checking are recorded on an error report form by the checker. Each error is sequentially numbered and brief details of the error are given.

b) Each error is categorised by the checker as detailed on the error report form. Additional comments may be included to cIarify the type of error.

c) On completion of the check the checker completes, signs and dates an error report front cover to summarise the findings of the check.

d) The completed error report is returned to the producer with the design details for correction.

e) On completion of all corrections the producer signs and dates the error report to this effect and returns the report with the design details for rechecking.

f) On completion of the re-check the checker signs and dates the error report to this effect. Any additional errors found during the re-check are recorded on a new error report which is fastened to the front of the original report.

g) Completed error reports may be submitted to a local review manager.

h) A 'nil return" process may be used in order to provide an audit trail.

3.3 Check Records Procedural check lists should be provided for completion by producer or checker to record progress through the checking process. Each step should be signed for





as it is completed. The producer hands the completed production check record to the checker with the design details for checking.

The check list should include any features associated with discernible error trends from the error reporting process.

An example is given in Figure El.


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Production Guidance



VERIFICATION INITIAL DATE REMARKS

checked copies have been obtained of design details from which those being checked have been derived

OPS and design specification have been examined to establish the exact scope of the scheme and obtain the scheme parameters

pertinent contract documents have been inspected, and familiarisation with local site information, the impact of adjacent or dependent work and other relevant correspondence

the design complies with the referenced standards it has been established that any standards declared in the development process are still applicable and valid

interface and liaison with other parties is sufficient the appropriate parts of GK/RC0706 have been referred to the presentation is clear, accurate, consistent and unambiguous the design complies with the client's requirements, as reflected in the design specification

operating requirements are satisfied availability criteria are satisfied reliability criteria are satisfied maintainability criteria are satisfied environmental issues have been fully considered the design provides an appropriate level of safety the design is simple the design is complete the design (including stagework) can be easily constructed the design is testable the design is functional and fit for purpose first principles are used any assumptions made are justified hazards are identified and the associated risks controlled calculations and / or functional safety analysis are performed where appropriate

appropriate check and / or error recording processes new work and interfaces are 100% checked existing installations are 100% checked in the relevant areas of circuitry or data altered

any copying of earlier designs, or use of standard computer aided design (CAD) cells, are treated as new work

design documentation is under complete control it has been established that the correlation process has been carried out and the records updated, where applicable

all the errors revealed by the production check have been corrected all the errors revealed by the independent check have been corrected certification is provided error records have been completed the check process is auditable technical checklist discernible error trends checklist

Figure El Typical Check Record


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Production Guidance



Part F Operating Requirements Review Once the scheme plan is substantially complete and before it is submitted for approval the Railtrack production manager’s representatives should be counselled at an informal pre-approval meeting at which the signalling facilities and operating requirements are reviewed.

The scheme plan or the general notes should be amended accordingly. Any decisions taken should be recorded in the design specification (see Part C), together with the reasons for the decisions.

These listings are representative, not exhaustive.

1 Scheme Plan Facilities

The representatives should be directed to consider, generally on a signal by signal basis:

a) signal box prefixes and numbering rationale;

b) changes in permissible speed imposed by signalling considerations, in accordance with GK/RT0007 (the juxtaposition of permissible speeds should be realistic to the driver’s ability to drive);

c) changes in line names;

d) manual block working;

e) bi-directional working (SIMBlDS is non-preferred);

f) method of working single lines, including one train working arrangements;

g) signal spacing curve used (from OK/P T0034);

h) unusual or substandard arrangements proposed, including deficient headway, passing clearances, standages, or signal spacing, excessive over spacing, use of a permanent speed restriction to obtain signal spacing, or sites with combinations of steeply rising and falling gradients, etc;

i) maximum acceleration / deceleration data of traction units that have route acceptance, where used in the determination of maximum attainable speed, e.g. in automatic level crossing regulation;

j) special requirements of any vehicles with route acceptance, such as traction compatibility with signalling equipment and any extra signal spacing distances or passing clearances at S&C required;

k) any possible sites of track circuit contamination and cases where axle counters are used in lieu of track circuits;

l) the provision of routes and route classes;

m) requirements for warning and permissive facilities, with risk assessments, where necessary;

n) any unusual or successive aspects in a sequence, including the inter-mixing of aspect sequences, such as isolated 4 aspect signals;

o) fixed distant signals;

p) special junction signalling, including flashing aspects or splitting distants;





q) the provision of route indicators and their display and avoidance of ambiguity with junction indicators;

r) signals with possible sighting problems, considering line curvature, reading through, over-bridges and proximity to other administrations’ lines;

s) whether red or white buffer stop lamps;

t) signals with critical standing room;

u) signal positions relative to station platforms;

v) signal positions relative to converging and diverging junctions and crossovers, particularly where trains reverse;

w) signal positions relative to level crossings;

x) existing automatic signals without replacement facilities;

y) train lengths for Lime Street controls at terminal (or other) stations;

z) signal positions relative to neutral sections, booster transformers, sub-stations, and track paralleling huts, etc. and their replacement facilities;

aa) signal replacement track circuit joints and any last wheel replacements;

bb) overlap lengths less than 183m;

cc) restricted overlaps and whether automatically selected;

dd) type of train protection/warning system provided, e.g. automatic warning system (AWS), train protection and warning system (TPWS), automatic train protection (ATP), trainstops, etc.;

ee) other SPAD mitigation provided,

ff) the need for any special station working arrangements, including DOO, and any TRTS, CD, RA or off indicators required;

gg) shunting signals related to operating movements;

hh) pre -set signals;

ii) method of control of level crossings;

jj) train detection indications approaching manually controlled barriers, whether automatic raise or automatic lower provided and, arrangements for initiating auto picture switching at CCTV crossings;

kk) special station schemes, including stopping/non-stopping selection, required for automatic level crossings;

ll) train activated warning systems, or other arrangements for personnel in areas of limited clearance;

mm) hot axle box detectors;

nn) the extent of train approaching indications and any special arrangements at fringe signal boxes;

oo) special acceptance arrangements with shunters or depots;

pp) access points and proximity of equipment to public access; and

qq) hazard detectors.


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Full opportunity should be taken to review any other features which relate to operating requirements or safety issues.

2 Interlocking Requirements

The following items affect the design of control tables and the interlocking (see GK/RC0706, Part F). These requirements should be recorded in the design specification (see Part C).

a) whether comprehensive approach locking, train operated route release (TORR) and / or automatic route setting (ARS) are to be provided,

b) where special approach lock releases might be required for long trains;

c) route locking that is time released to allow an opposing route;

d) method of flank protection and / or split detection or separate end numbering to be provided,

e) whether track section overrun protection or special SPAD detection facilities are required;

f) whether warning routes are required to step up and down automatically;

g) preferred routes and overlaps;

h) shunt overlap lengths and provision at main signals;

i) tunnel signal controls;

j) whether direction arrows are required for bi-directional working;

k) the operation of ground frames and type of release, approach locking, etc.;

l) type of trap point restoration (automatic is non-preferred);

m) any omission of track controls from shunting signals;

n) working of slots or routes between signallers' areas; and

o) provision for override facilities and whether selective; also other standby arrangements.

3 Signalling Control and Display System

Signaller's facilities, including telecommunication and train describer systems, should be similarly reviewed (see GK/RC0706, Part L) and recorded in the design specification.

The ergonomics of the signaller's control system and visibility of the display system should be particularly considered.





4 Other Scheme Pre-Approval Issues

4.1 Recording of Technical Standards The standards used should be documented in accordance with GK/RT0201. They should be listed on the scheme plan general notes or interlocking reference sheets (see Part N). A typical certificate of compliance is given in Part C

4.2 Systems Approval Systems, including software, should be approved in accordance with GK/RT0104. A suitable format for a safety case is described in ENV 50129. Additional controls for software are defined in pr EN50128


Signalling Design:

Production Guidance



Part G Design Modifications

1 Categories of Design Modification

Where design details require modification or amendment after production, the following categories should be distinguished: (Only the method outlined in Section 1.1 is applicable for data.)

1.1 After Issue but before Construction has Commenced Confirmation should first be received from site that construction has not commenced.

1.1.1 Existing Installations The modification should be incorporated into the original red / green alteration in red and green. It should then be rechecked and issued as a new version. This category may also be applied to control tables before the commencement of testing, providing they have not been issued for data preparation.

The preferred method is for the modification to be applied using the medium for production. If the medium for production has already been updated to become the commissioning record, then the use of modification sheets is preferred.

1.1.2 New Installations The respective sheet(s) should be redrafted to incorporate the modification and should then be rechecked and issued as a new version.

1.2 After Construction has Commenced but before Testing Every modification in this category should treat all previously issued work as having been installed. Thus, when the "two drawing" method is in use, modifications should only be applied to the 'red" sheet.

Modifications may not be cancelled once construction has commenced. The designer should treat the construction as completed, and rectify it with a subsequent modification.

Once the test copy has been issued, every modification should be registered by obtaining a test log number from the tester in charge.

1.2.1 Existing Installations The use of modification sheets is preferred for circuit diagrams. These should reference the original sheet number and version.

For other drawings and for large scale modifications to circuit diagrams, after the commencement of construction, a whole sheet may be reissued under a new version on which modifications are superimposed in blue upon the original red / green alteration. See Figure G1 for an example. The preferred method is for the modification to be applied using the medium for production. If the medium for production has already been updated to become the commissioning record, then the use of modification sheets is preferred..





Figure G1 Large Scale Modifications Before Testing - Existing Drawings


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Production Guidance



Figure G2 Large Scale Modifications Before Testing - New Drawings





1.2.2 New Installations The use of modification sheets is preferred for circuit diagrams. These should reference the original sheet number and version.

Alternatively, as the design for all new work is uncoloured, the respective sheet(s) may be redrafted to incorporate the modification in red and green. See Figure G2 for an example. They should then be rechecked and issued as a new version, together with an uncoloured updated version.

1.3 After Testing has Commenced or After Issue of the Closure List Modification sheets should be used.

Once the test copy has been issued, every modification should be registered by obtaining a test log number from the tester in charge.

2 Modification Sheets 2.1 Principle Uniquely identified modification sheets should be issued by the design authority. Modification sheets may be produced in response to a test log, a construction log, or other change request. See Figure G3 for an example.

2.2 Method Modifications should be produced and independently checked by suitably qualified designers in accordance with GK/RT0201. The producer should complete the following copies:

• top (white) construction copy; • second (pink) test copy; • third (green) design copy, to be retained; and • other copies as stated in the design specification.

The construction copy should be drawn in red and green. The convention for new and recoverable items should be clearly identified to suit the transmission medium (e.g. if a black and white method is used for circuit alterations, then new wires should be ringed and wires to be recovered crossed through).

2.3 Issue When modification sheets are issued from the design office, they should be sent with an issue document and a new version of the index showing the affected sheet and the serial number of the modification sheet.

2.4 Endorsement of Other Copies As soon as practicable, a designer should transcribe the circuit modification in blue onto the production office copy and the maintenance record copy on site, quoting the serial number of the modification, The transcription should be independently checked, signed and dated. The other site copies should have the appropriate copy of the modification sheet attached to the top right hand corner of the affected sheet.

2.5 Electronic Transmission Where it is necessary to transmit altered sheets to site electronically a black on white single copy should be transmitted. The recipient should be asked to transmit the received sheet back again for comparison with the original. Only when the accuracy of the transmitted sheet has been confirmed by telephone may the modification sheet be considered as validated. The standard copies should be subsequently sent in the normal way and endorsed with the method of electronic transmission.


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Figure G3 Typical Modification Sheet (Construction Copy)

Activity Complete Date

Commissioning CopyUpdated

Produced JMG 1/6/92

Checked SDH 2/6/92

Construction

Testing Completed

ModificationSerial NumberYS 0123

Issued 3/6/92Place Toft Green RR

Test Log Number Sheet Number

FD TPR

R1

FD TPR N

FD TPR RL

C7

C8

R2

C4 C3

FD2TPR

C1 C2

NEW WIREREDUNDANT

Prep. Inspection

Prep. W.C. and Cont.Prep. S. & F./C.F.T.Prep. cores Loc. endPrep. cores Equip. endChangeover complete

Westway Signal Company MODIFICATIONSHEET

1158E- 42 Version AA2002

FD2TPR





3 General 3.1 Site Design Resource It is recommended that for large commissionings, a minimum of two designers be on site; and for small commissionings the design office be manned and electronic transmission used.

3.2 Successive Modifications When it is necessary to commence the production of subsequent alterations before the completion of final records, in accordance with the requirements for overlapping design in GK/RT0201, any modifications should additionally be transcribed onto the production office and site copies of each of the subsequent alterations.

This process (which should also include any security copies of previous, not yet commissioned, alterations) should be fully controlled by the responsible design engineer.

3.3 Approval for Construction All modified details issued by the design authority require the usual approved for construction signature on the approvals and issue record (AIR), as described in Part K. Railtrack should have procedures in place to accept modifications issued on site without access to the AIR.

3.4 Updating of Modifications The process for updating modifications is described in Part J.

3.5 Superseded Drawings The design authority should agree construction procedures to control the removal of superseded drawings.

However, superseded sheets may be retained on site, suitably endorsed, if required by installers as a record of wires previously run.


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Part H Certification Process The following are typical processes that fulfil the GK/RT0201 certification requirements:

1 Design Production 1.1 Production Office Copy Usually the production office copy is the initial hand coloured print of the altered source record. However, if the checking copy is the initial hand coloured print, the production office copy should not be obtained until after the checking process. The production office copy should then be coloured and checked like-for-like with the checking copy as described in Section 2.2

1.2 Checking Copy A checking copy should be obtained. This may be one of the following, depending on the production method used:

a) a colour copy of the production office copy; b) the initial hand coloured print of the altered source record; c) a copy of a production master; or d) a CAD colour plot.

Different checking copies may be used by the producer and checker, or, provided any tick markings are in different colours, the same copy may be used. The checking copy may be subsequently used as the production office copy provided that the latter is not required for the reproduction of duplicate prints as described in Section 2.1.

1.3 Production Check When the design has been reviewed by the producer any necessary corrections have been incorporated, and it is ready for independent check, the producer should sign and date the production office copy.

1.4 Independent Check When the independent check is complete, any necessary corrections have been incorporated and, if applicable, it is ready for approval, the checker should sign and date the production office copy

1.5 Corrections Note that any corrections should be made to the checking copy (before independent check), the production office copy, the source record ("two drawing" method) and the production master (if applicable).

2 Production Issue Copies

2.1 Colour Copier Method If the production office copy is being colour copied to provide the issue copies, the production office copy should first be signed so that the duplicate prints require no further signature, only inspection of colour balance. Sheets may also be date stamped before copying. The “Production Office Copy" endorsement should not appear on the duplicate copies.

22 Manual Colouring Method If the production office copy is being manually copied to provide the issue copies, duplicate prints should be taken from an unsigned source record, then manually coloured by a competent person who should sign each print as produced. It should be checked like-for-like with the production office copy by a competent person who should sign it as checked. The signed initials certify that the print is an accurate copy of a fully certified production office copy.





3 Updated Records 3.1 Source Record When the source record has been updated by a competent person, referred to as the producer of the update, and all commissioning modifications incorporated, the update block on the source record should be completed in accordance with Part J.

3.2 Checking Copy A checking copy may be obtained. This is generally a print of the updated source record. One checking copy may be used by both the producer and checker, provided that any tick markings are in different colours. The checking copy may be used as the master record provided that, if the checking copy is tick marked, the master record is not required for the reproduction of duplicate prints, as described in Section 4.1.

3.3 Checking from the Master Record When the update has been reviewed by the producer of the update, any necessary corrections have been incorporated on the source record, and it is ready for independent check, the producer should generally obtain the master record and sign and date it.

When the independent check is complete and any necessary corrections have been incorporated on the source record, the checker should add printed initials to the update block on the source record and sign and date the master record.

3.4 Checking from the Source Record If the master record is required for the reproduction of duplicate prints, as described in Section 4.1, it may bear the produced and checked signatures. If however, for minor updating, all checking is done by inspection of the source record, the master record need not be obtained until the update has been fully checked.

4 Record Issue Copies 4.1 Copying from the Master Record If the master record is being copied to provide the issue copies, the master record should first be signed so that the duplicate prints require no further signature. Sheets may also be date stamped before copying. The “Master Record" endorsement should not appear on the duplicate copies.

4.2 Copying from the Source Record If the issue copies are not taken from the master record, duplicate prints should be printed in black and white from an unsigned source record, and require no further checking. A competent person should sign each print as produced. These signed initials certify that the print is an accurate copy of a fully certified master record.

5 Approval and Issue Record Sheet

The certification requirements are given in GK/RT020I. See also Part K.

6 Issue Documents The issue document should be prepared and signed in full by a competent person and should denote the company responsible.


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7 Variations 7.1 CAD Colour Plotting Where issue copies are individually colour plotted (e.g. for scheme plans and bonding plans), only the producer's initials are required in order to verify that the colours agree with the production office copy and have not been corrupted.

7.2 Additional Certification Block In the following circumstances it may be necessary to apply a separate certification block for the produced and checked signatures:

a) using an existing CAD master record to create a green copy; b) modifying production copies in blue; c) undertaking correlation corrections on the master record, d) verifying drawings from other parties; or e) certifying a data Iisting or other items without title blocks.

Any new drawing number and, for production copies, the date the source record is updated, should be incorporated into the certification block. If a new version is created, this should also be incorporated in the appropriate colour.

7.3 Data Systems Data files should be certified on the status record index, against each filename. The initials of producer and checker on the data disk (or equivalent) label certifies that the data files are an exact copy of those on the hard disk.


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Part J Source Record Updating

I "One Drawing" Method So as to simplify the modification process, source records that require updating should not generally be updated prior to commencement of construction, unless the relaxation for overlapping work, given in GK/RT020I, allows it.

The following items should be considered in the updating of records;

a) The production of design details by the "one drawing" method should be done in a manner which is conducive to the updating of records;

b) All green work should be removed; c) All red work should be added; d) All design, construction and commissioning modifications should be

incorporated (see Section 3); e) All relay contacts and terminals, etc, made spare by the work, but left in situ,

should be removed from circuit diagrams (but not from analysis and layout sheets). Relay contact sheet numbers (and numbers of wires) should have been coloured green on analysis sheets, requiring their removal;

f) Angled wires left after an alteration should be squared up and straightened out;

g) Congested areas should be re-spaced where recoveries have been made; h) Care should be taken to ensure that only relevant notes are transcribed The

notes may also require some rewording, but without changing the intention.

2 "Two Drawing" Method

Using the "two drawing" method combines design production and updating. The source records used to prepare the red copies show the altered arrangement and are retained for record purposes.

However, the following items should be considered before the source records can be considered to be updated:

a) all design, construction and commissioning modifications should be incorporated (see Section 3).

b) all relay contacts and terminals, etc, made spare by the work, but left in situ, should be removed from circuit diagrams (but not from analysis and layout sheets).

c) care should be taken to ensure that only relevant notes are retained. The notes may also require some rewording, but without changing the intention.

3 Updating Resulting from Modifications

3.1 Modification Process The modification process is described in Part G.

3.2 Pre-Commissioning Modifications Source records should be updated before the commissioning to include all design and construction modifications issued by that time. This allows maintenance records to be provided on site at the time of the commissioning.





3.3 Post-Commissioning Modifications Source records should be further updated after the commissioning to incorporate any commissioning modifications into the final records.

The pink test copy of the design details and any remaining green designer's copies of modification sheets, should be returned to the design authority within 48 hours of commissioning in order to initiate the final record update. The test copy (together with any pink test copies of modification sheets) should then be returned to the records custodian.

3.4 Design Authority Interface Management Responsibilities for record updating should be clearly defined in the design specification (see Part C) or method statement (see Part L).

Where a design authority is sub-contracted to work at a particular site for another design authority, a distinctively coloured additional copy may be provided on site for return to the sub-contractor after modifications have been transcribed on to it to facilitate updating for records. Once the sub-contractor's copy has been returned, any further modifications should be sent on modification sheets.

4 Update Control The version in the title block should be incremented whenever source records are updated in accordance with Part K.

An update block should be placed next to the title block of each source record, as shown in Figure KI, and the following details completed whenever the source record is updated (alterations, corrections or modifications), in order to identify its status:

a) version, as shown in the bottom right hand corner of the sheet; b) printed initials of the producer of the update; and c) printed initials of the checker (left blank until the update has been checked).

An entry in the update block signifies that the source record has been updated to a fully checked production copy of the appropriate version and that items listed in Sections 1 and 2 have been considered. For the final version it also implies an inspection of the test copy and updating to all relevant modification sheets and commissioning modifications,

Where space is restricted, previous entries may be compressed. Redrawn or renumbered sheets should be suitably identified and any previous numbers quoted.

When using the “two drawing" method, if none of the items listed in Section 2 apply, the update block may be endorsed "N/A”.

5 Updating of Scheme Plans

A signalling plan should generally be derived from an updated scheme plan. Likewise a copy of the signalling plan may be renumbered and renamed for use as a scheme plan with the addition of proposed alterations.

However, as explained in Part K, the method of version control and the numbering system (see GK/RT0201) is different for each. (The alteration letters of the signalling plan should correspond to those used for the engineering details.)

Consequently, these details should be amended as part of the update process.


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Part K Configuration Control

1 Identification The following means of displaying information should be used to uniquely identify design details and their status at each phase of a signalling scheme. (Copies of design details should also be endorsed with their purpose, as described in Part D.)

All dates should be given in the order day, month, year. For new work, a four figure year format should be used.

1.1 Title Block Design details (except those covered by Sections 1.2 or 1.5) should include an overall border of 5mm with a left hand binding margin of 40mm minimum, with an update block, production block and title block agreed by the records custodian bearing the information required by GK/RT0201. A typical layout is shown in Figure KI. The border and title block should be an integral part of the design. (For alterations to existing design details see GK/RT0201.)

Source Record Updated

Version Prod. Check

ProducedChecked

Issued

Infrastructure Controller

Printed & signed initials of producer anddate passed to checker

Printed & signed initials of checker anddate independent check completed

Issue dateScale as required

Interlocking control area

Design detail type and/or description

Signal box or control point

Update Block (see Part J)

Filename or contractor’sreference number

Design Authority/Location

RAILTRACK

Drawing Nº

Last Full DateCorrelation VersionCurrentVersion

Version (see Section 3.5)

Records Custodian

Production Block(entries blank on source Record)

Figure K1 Typical Update Block, Production Block and Title Block (Not to Scale)

1.2 Data for Programmable Systems The actual requirements of an electronic system should be specified in the appropriate system applications manual.





1.2.1 Listings Data listings (and difference lists, where prepared) should either have a title block applied to the front sheet to incorporate the drawing number, version and the initials of producer and checker, or have the necessary information included on the first page of the data print-out.

Difference lists should also indicate both versions of data compared.

1.2.2 Electronic Data Media Data disks and other electronic data media should bear a label containing the information shown in Figure K2. These should be accompanied by status record index sheets (see Section 2.4).

Figure K2 Typical Data Disk Label

1.2.3 Erasable Programmable Read Only Memory (EPROM) EPROMs should bear a label containing the following information:

a) site reference (signal box / interlocking); b) data type (system / sub-system); and c) version / subversion number.

They should be accompanied by status record index sheets (see Section 2.4).

Production EPROMs used in the signalling equipment should be identified with a white label.

Master EPROMs used for verification purposes may be identified by colour coded labels, defined in the appropriate system applications manual.

1.3 Scheme Approval Scheme plans should bear an approval and version panel on the right hand end, as shown in Figure K4.

1.4 Mechanical Design See Part N, Section 4.10 for a typical mechanical drawing grid.

1.5 Other Design Details Design details for which it is not practicable to provide a title block, e.g. signaller’s route cards (see Part N, Section 5.4), should be given a suitable means of identification and certification. See Part H for details.

Design AuthorityMaster Disk (1) or Master Disk (2)

Produced JMG JMG 1/4/92

Checked SDH SDH 5/5/92

IdentifiesStatus Record Index 1158TD-DB1X

alterationIndex Version AA1Software Version 0.3

Identifies interlocking Signal Box Hudson Streetand sub-system Disk No. 1158TD-DB1


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Manufacturer’s operation and maintenance manuals (see Part N, Section 5) should carry the following information, allocated by the manufacturer:

a) unique identifier, e.g. document number; b) version and / or date; and c) name of manufacturer.

2 Indexing 2.1 Information Required Index sheets should be provided at the front of all sets of design details to enable the contents to be audited. They should contain a complete list of sheet numbers, preferably including any spare numbers, and should contain the following information for each sheet, as shown on the typical example given in Part N, Figure N11:

a) sheet number; b) current version; c) title of description of drawing; d) status (i.e. red, green, combined, new, abolished); e) serial numbers of any modification sheets issued; f) columns for the use of testers when the index sheet is used as a closure list

(see Section 2.5).

Updated record copies should show columns (d), (e) and (f) blanked. The provision of index sheets renders the note “Sheet n of N Sheets” superfluous. It should be removed from existing sheets at a suitable opportunity to reduce the risk of error.

2.2 Arrangement of Index Sheets Index sheets should be numbered in the same series as the drawings to which they apply, as specified by the records custodian. The index sheet(s) should consequently be listed first on the index. The approval and issues record (AIR), however, should not appear on the index sheet as it is separately controlled (see Section 3.4.4).

Any remaining design details, associated with a particular interlocking, not forming part of a set should be grouped together on a single index sheet. An index of indexes may be provided.

Production copies of design details should include index sheets as part of the design, with alterations shown on them in red and green. Red and green sheets may bear different versions. Renumbered or abolished sheets should also be identified. Where convenient, red and green sheets may be shown on separate rows on the same index.

2.3 Lineside Locations Index sheets should be provided for each apparatus housing or for each suite of apparatus cases forming a single lineside location. A non-scaled extract of the location plan should be provided on the index sheet, showing the geographic area controlled from the location. (See Part N, Figure N11 for an example.)





Sub System or

Module EPROM Ser No Checksum

Version/ Sub

Version Fileman or EPROM Reference Name Produced Checked

HUDSON STREET

IECC B

Database Disk 5 Status Record Index Sheet

No. 1158B-DB5X

Figure K3 Typical Status Record Index Sheet for Software


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2.4 Indexing of Data Systems Status record index sheets (or other system specific documentation, such as central interlocking status records and installed SSI software records), giving the current software version of each data file, should be provided for each master data disk (or equivalent) belonging to each electronic system or sub-system. EPROMs should also be identified by means of status record indexes. Status record indexes should be treated as design details in the same way as index sheets, complete with a standard title block bearing a drawing number and version with alteration letters. See Figure K3 for a typical example.

Electronic systems should provide the means of complying with these requirements, either by detailed procedures or from within the system design software.

2.5 Closure List At a date to be agreed between the responsible design engineer and the tester in charge (which should be stated in the design specification and should be at least three days before the commencement of commissioning testing), a closure list should be issued to the tester in charge, comprising an updated set of index sheets listing the latest version of every sheet of design details issued. It should be printed on pink paper and endorsed “Closure List”.

This set of index sheets should be issued to the tester in charge under a single issue document (see Part H), and so, where several design groups are issuing work for the same commissioning, it is the responsible design engineer who should issue the complete closure list.

However, if the commissioning is divided into several work packages (see GK/RT0201), a separate closure list should be issued for each package.

For the control of modifications see Part G.

3 Change Recording 3.1 Principle Changes to design details should be documented and version controlled.

For version control purposes a distinction should be drawn between the following:

a) proposal-type drawings for consideration, as described in Section 3.2 (the source record should not be altered); and

b) design details for production, as described in Section 3.3 (the work may be applied to the source record and alteration letters should be used).





Version Description of Amendment Source Record Amended

Date Prod. Check A Initial design. 1/9/90 GL JG B Overlaps revised following risk assessment. 1/2/91 SDH JG C Track circuit EK cut-sections to replace banner.

Track circuit FD cut-sections for permissive working. 1/8/91 GL RC

Approval in Principle (98-YS-5001/1 to /5) Designation Date Signature Responsible design engineer 14/8/91 RDE Railtrack production 1/9/91 RTP Railtrack infrastructure 3/9/91 IFT D Signal sighting amendments:

Signal 105 was at 175.561 (not significant amendment for approval purposes)

3/3/92 GL RC

WORKS COMMISSIONED 6/6/92

Statutory Approval Status No objection to concept received 1/10/90 No objection to proposals received 2/9/91 Certificate of completion sent 1/6/92 Works inspected Statutory approval received Westway Signal Company RECORDS: YORK RECORDS CENTRE RAILTRACK 98ys50015.dgn

TOFT GREEN RESIGNALLING

Drawing Nº 98-YS-5001/5

Produced GL GL 4/3/92 SCHEME PLAN Last Full Date Checked RC RC 7/3/92 TOFT GREEN JUNCTION Correlation Version Issued Sheet 5 of 5 Current

Version D

Figure K4 Typical Approval and Version Panel for Scheme Plans


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3.2 Proposal-Type Drawings 3.2.1 General The reason for any modifications or amendments required to scheme plans, signal sighting notes, level crossing ground plans and other proposal-type drawings should, after the commencement of change control be recorded in an approval and version panel. A number of changes may be grouped together provided they are checked at the same time.

An example of an approval and version panel for scheme plans is shown in Figure K4. Other design details should incorporate a small version panel (similar to the top part of Figure K4) within the drawing border.

3.2.2 Approval Status The approval status of the scheme plan should be recorded on the scheme plan source record in the Approval and version panel as described in GK/RT0201. The statutory approval status of the scheme (i.e. letter of no objection received, etc.) should be similarly recorded.

Recording this information does not constitute a new version of the scheme plan.

Railtrack should ensure that the holder of the source record is informed of any change in status.

3.2.3 Version Control The initial design, after being checked, should carry the version letter “A”, after which sequential letters should be used, starting with "B" for the first change. The version letter for the change should appear in the version box in the bottom right hand corner of the drawing, and should generally be shown red on coloured plans.

3.3 All Other Signalling Design Details Alterations to design details (including all new work) should be recorded on an approval and issues record (AIR) and version control applied in accordance with Sections 3.4 to 3.6, as appropriate.

3.4 Approval and Issues Record sheets (AIRs) Any alterations, modifications or amendments required to design details should be recorded on a separate AIR for each alteration undertaken at a particular installation. (The records custodian should specify the policy for determining installation boundaries.)

The approval to issue for construction should be recorded in the appropriate column on the AIR prior to issue.

The process is illustrated in Figure K5 and an example of an AIR is given in Figure K6.

3.4.1 Change Information The AIR should provide an auditable history of all changes made at an installation in chronological order. The current version of each sheet which appears on the index should be derived in accordance with Section 3.5. The AIR should give a complete list of altered, modified or amended sheets, together with a description of each change. It should also record the issue date of the production and record copies. The AIR should identify renumbered or abolished sheets and, where the 'two drawing" method is used, the '“red" and "green" sheets should be separately listed.

3.4.2 Responsibility Responsibilities for entering and certifying the information are given in GK/RT0201.





Figure K5 Version Control Pictogram


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Figure K6 Typical Approval and Issues Record Sheet





3.4.3 Alterations A new AIR sheet should be started for each alteration which it is intended to commission on a single occasion. Before the alteration is begun, the producer should ascertain that all previous AIRs in the same area have been signed to confirm the preparation of final records. If not, the requirements of GK/RT0201 for overlapping design should be applied. If, in the case of like-for-like renewals, or temporary work, no records require to be updated (see Part L), a suitable note should be made in the distribution column.

3.4.4 AIR Copies A master copy of the AIR should be created for certification. Details of subsequent versions should be inserted on the signed master copy.

The AIR version is defined by its content and does not require to be separately version controlled.

A copy of the appropriate signed AIR should be included with each set of production copies issued.

3.4.5 Retention of AIRs The signed master copies of AIRs should be retained by the records custodian for the life of the installation.

3.5 Version Control 3.5.1 Alteration Letters Every alteration which it is intended to commission on a single occasion should be given separate alteration letters. (This includes correlation corrections, all new work planned maintenance alterations, each stage of a multi-stage scheme and each work package within a stage.) The records custodian should allocate the letters sequentially on commencement of each alteration, using a two character alphabetic series for each installation, i.e:

AA, AB, AC, etc.

If any letters allocated are not used, a blank AIR should be returned for that alteration.

3.5.2 Change Numbering Each version of production copies should be given a change number; starting at “1” for the original version, with subsequent numbers being allocated to modified or amended versions.

A line should be ruled across the AIR to separate the details of each version.

The full version reference consists of the alteration letters and the change number, e.g. “AA1”. Each source record should bear the current version in the bottom right hand corner, which may be coloured on production copies.

The final version should encompass all modifications issued during commissioning. This entry should list or reference all final records being returned to the records custodian, with a separate note of any new, renumbered or abolished sheets.

Special control should be applied where it is necessary for a batch of modified drawings, being issued together, to be given the same change number, but only some of the drawings have been previously modified. In this case, the lowest change number available to all the sheets should be used, although the previously unmodified sheets would never have carried the previous number. A note should be added to the update block on such sheets, stating that the previous version is not used. It is always necessary to apply this control where sheets are renumbered, to prevent the reuse of a sheet number with a version already used.

Any intermediate change numbers that are not used at all should be stated on the AIR.


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Note that, where the two drawing method is used, red and green sheets may carry different change numbers.

3.5.3 Commissioning Alterations need not be commissioned in alphabetical order of alteration letters, provided that the design has been produced to cater for this.

3.6 Version Control of Data Systems 3.6.1 Version Numbers The status record index (see Section 2.4) should give the current software version of each data file. The version number (first part) should be incremented (and the sub version reset to zero) for each commissioning that necessitates a data change, and the sub version (second pad) should be incremented each time the data is changed prior to re-testing, irrespective of whether EPROMs have to be reprogrammed for the re-testing.

Data files may alternatively be version controlled in accordance with Section 3.5 using alteration letters.

3.6.2 Traceability and Certification All certified data, when downloaded onto an EPROM, disk, or other electronic storage device should be accompanied by a copy of the software status record index. The status record index should be version controlled in accordance with Section 3.5.1, bearing the appropriate alteration letters in the current version field.

This allows altered software to be associated with other design details issued for a particular commissioning (although software modification may not necessarily relate to an infrastructure change).

3.7 Design Tools All design tools, including data preparation software, computer aided design (CAD) cells, templates, standard drawings and typical circuits (see References), should be version controlled as required by GK/RT0201.

Drawings should bear a small version panel giving brief details of revisions, certification and, where applicable, type approval status.

See Part E for safety integrity and verification requirements.


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Part L Design Production in Special Cases Relaxations in the design process are available for temporary work and non-conceptual work.

I Control Measures In order to make use of these relaxations, control measures should generally be arranged in accordance with the following principles:

a) the final records for all previous alterations should be complete, unless covered by a relaxation in GK/RT0201;

b) the strategy for any stagework should be identified in the design specification (see Part C);

c) the affected wiring should be correlated as far as reasonably practicable (see GK/RT0201);

d) all the relevant diagrams, including analysis, cable core plans and bonding plans, should be produced and issued for production, testing, commissioning and maintenance purposes, except for non-conceptual work (see Section 3);

e) temporarily out of use, not yet commissioned and redundant circuitry should be identified on the production and subsequent record diagrams by the use of special notes or symbols, as described in Section 4.1 (but non-conceptual temporary alterations to circuitry need only be identified on the maintenance record diagrams);

f) trackside equipment that has temporary alterations, is temporarily out of use, not yet commissioned, or redundant and left in situ should be shown on record signalling plans, as described in GK/RT0004;

g) not yet installed trackside equipment with circuitry provided in the interlocking and recovered trackside equipment with circuitry left in the interlocking should also be shown on record signalling plans, as described in GK/RT0004;

h) temporarily out of use, not yet commissioned and redundant controls, where the circuitry (or mechanical locking) is left in the interlocking, should be shown on record control tables, as described in Section 4,2; and

i) the principles for the disconnection of redundant/temporarily out of use wiring laid out in GS/IH1D20, or GT/EH H802, as appropriate, should be followed at all times.

2 Temporary Work (Major)

Temporary work is defined as alterations which remain in use for a limited period of time. This section (Section 2) generally applies to major works and associated temporary stagework. Where temporary work is non-conceptual in nature, then Section 3 should be applied instead. Stagework that is not temporary should comply with the full requirements of GK/RT0201.

Relaxations in the technical requirements for temporary work are given in GK/RC0706, Appendix B3.

The likelihood of the design process integrity being jeopardised by these relaxations should be addressed by a risk Assessment that considers the following factors:

a) the time for which the work may remain; b) the likelihood of future Alterations to the temporary work;





c) the possibility of protracted timescales, requiring imposed solutions in the event of slippage; and

d) the introduction of temporary work on life-expired equipment with no maintainability.

Guidance on risk Assessment is given in Part R.

2.1 Examples The following are examples of temporary work to which the relaxation of Section 2.2 applies:

a) Short-lived alterations to circuitry during permanent way works after which all signalling returns to the previous arrangement (either to maintain point detection, and disconnection of affected routes, or to maintain track circuit operation following temporary removal of defective switch and crossing components).

b) Short-lived new work and alterations to circuitry during disarrangement of locking or long term civil engineering works after which all signalling returns to the previous arrangement (including the temporary provision of automatic signalling or single line operation).

c) Stagework (progressing towards an approved overall scheme) that will be removed at a subsequent stage.

2.2 Relaxation for Temporary Work It may be beneficial to use the “two drawing” method described in Part D, but without altering the source records. The temporary alterations should be coloured red (and green) for the first stage and green (and red) for the second stage.

Other expedients are not permitted for temporary work (unless it is non-conceptual as described in Section 3). In particular, no relaxation should be granted to the requirement for independence between design production, checking and testing functions.

It is essential that the source records remain in the possession of the responsible design engineer whilst the temporary work remains in force. Otherwise the full requirements of GK/RT0201 should be applied.

A separate set of circuit diagrams should be produced for the introduction and abolition of the temporary work, irrespective of the timescale between the two stages. Each stage should be clearly identified on each drawing or book of diagrams.

Record and version control should be applied in accordance with Part K, with a new version for the temporary arrangement. Provided the design is restored to its original arrangement after the second commissioning, the second records issue should bear the original version, in correspondence with the unaltered source records. If, however, the source records have tote altered, then the version should be updated for the altered sheets.

A full issue of installation and testing

details and maintenance records, including analysis (see Part N), should be made for both stages in accordance with GK/RT0201.


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3 Non-Conceptual Work Work that does not introduce new design features to a system. This section (Section 3) is generally confined to maintenance design and like-for-like work

Relaxations in the technical requirements for non-conceptual work that is temporary in nature are given in GK/RC0706, Appendix B3.

3.1 Examples The following are examples of non-conceptual work to which the relaxation of Section 3.2 applies:

a) Temporary speed restrictions (TSRs) involving the disconnection of AWS inductors associated with the planned application of a TSR, where permitted in GK/RT0038.

b) Release of controls for engineering work or single line working, in accordance with Rule Book, Section E. See GK/RT0231.

c) Renewal of standard equipment or cables (see GK/RT023I), including the replacement of missing equipment, or emergency renewals following an incident. Any unforeseen alterations to circuit diagrams or equipment profiles should be annotated on the diagrams.

d) Replacement with operationally equivalent equipment as defined in GK/lRT0231, e.g. changing the type of point detector, point machine, or signal head; upgrading track circuit connections, disconnection boxes, or cable terminations; changing the type of secondary cell; changing a lock and controller for a combined type; and renewing an interlocking tappet without a redundant notch.

e) Special arrangements defined in GK/RT0231, such as temporarily strapping out point detection; plain lining the bonding at damaged S&C; and strapping out redundant equipment where permitted in GK/RC0706, Appendix B3.

f) Other temporary disconnection or strapping for maintenance purposes.

g) Renewal of cables, where a different type or size of cable has to be used. See GK/RT0213.

h) Rectification of cable faults, using red cable fault jumpers to spare conductors, in accordance with GK/RTO23I.

i) Like-for-like switch and crossing renewals without altering the track circuit bonding: The permanent way engineer’s plan should be compared with the bonding plan for the like-for-like status of the renewals to be confirmed. However, any clearance or bonding deficiencies should be corrected at this time, unless the work would not be merited by the achievable risk reduction (see GK/RC0706, Appendix B2). The GK/RT0011 requirement for clearance points and other insulated rail joints should be observed in the design and checked on site after construction. See GK/RT0252 for bonding requirements.

The permanent way engineer's plan should be annotated with the position of the insulated rail joints (IRJs), extended sleepers and other requirements.

3.2 Relaxation for Non-Conceptual Work Where work is capable of being designed completely by alterations superimposed on record prints and this is documented (e.g. in the design specification or in method statements), temporary Alterations may be undertaken from maintenance record copies of circuit diagrams. The alterations should be shown initially on the prints in green and red.

The documentation should state the responsibility for arranging for the records to be updated (see Part J) and prints issued. Where the source records are not





held and the work is not like-for-like, the infrastructure controller should be informed of the alterations within 48 hours of their commissioning.

Other expedients are not permitted for non-conceptual work. In particular; no relaxation should be granted to the requirement for independence between design production, checking and testing functions.

The annotated production details should be endorsed with a new version (see Part K) and a copy of the final alterations, including rack layouts and analysis (see Part N), incorporating any commissioning modifications (preferably the test copy), should be provided for updating purposes. However, updating is not required if the final arrangement is confirmed as being like-for-like (see Section 3.3).

A full issue of maintenance records should be made in accordance with GK/RT020I.

3.3 Like-for-Like Work Like-for-like replacement is a special case of non-conceptual work, defined as 'the removal and restoration of an item of equipment, including a cable, which has been operating correctly and where the work does not require any change to diagram".

For genuine like-for-like work (i.e. replacing an item of equipment or cable with the same type and size), no records are required and the source records and their version should remain unaltered.

It may be beneficial to produce a full set of circuit diagrams using the 'two drawing" method described in Part D, but without altering the source records. Items being renewed should be coloured green on the "green" copy and red on the “red" copy.

In other respects Section 3.2 should be followed.

4 Presentation of Partially Commissioned

(or Out of Use) Design Details

Any non-standard abbreviations, symbols, or notes should be fully defined on every sheet used.

4.1 Circuitry If the circuitry for the final arrangement is to be installed on one occasion, but commissioned in stages, circuit diagrams for the final arrangement may be used for each stage, endorsed to identify circuitry not in use at that stage. Only diagrams issued for the first time should be endorsed 'ALL NEW WORK' in red

Circuit diagrams should show all not yet commissioned (and redundant) circuitry and equipment in situ.

Partially commissioned (or redundant) circuitry should be identified on the production diagrams by the use of notes with arrows, or symbols which should be defined on each sheet. These should generally be coloured red.

Where a whole drawing, or discrete parts of a drawing, depict partially commissioned (or redundant) circuitry, the drawing, or the discrete parts bounded by a border, should be endorsed with the appropriate note.


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The following notes may be required:

a) Where a busbar fed circuit is not in use, the fuse should be shaded over in green, with the note "DUMMY FUSE" in red.

b) Relays require the note "NOT IN USE" beside the coil.

c) In coming and outgoing circuits require the note "NOT IN USE" beside the circuit name.

d) Conductors to be disconnected should be identified with the standard symbol from GK/RT0205.

e) Where looping cannot be identified from the circuit diagrams, where necessary to maintain the integrity of the looping, it should be marked "TO BE DISCONNECTED, THROUGH-CRIMPED AND INSULATED".

f) Where cables have not yet been installed or terminated, the notes "NOT INSTALLED" or "NOT TERMINATED" are required. Cables should not be partly terminated.

g) Temporary stagework circuits, or jumpers, should be run in colour coded conductors (blue, orange, violet, brown or grey) and the appropriate code added (see Part M, Section 6.1).

h) If a circuit is to be disconnected at a termination link, the link should be shaded over in green, with the note 'lNSULATED BATTEN - LINK REMOVED" in red.

i) Where stagework cables are connected to one side of disconnected links in order to form single post terminations, a note such as "RED DOMED NUT" should also be added to remind installers to fit precautionary devices to the terminals

j) Where power supplies are not yet in use the note "TO BE LABELLED 'FUSES/LINKS DISCONNECTED - DO NOT RECONNECT’" is required beside the BS 88 fuses and links and the note "TO BE PADLOCKED OFF" beside any lockable fuse switches. Compliance with the Electricity at Work Regulations should be ensured. (See GK/RC0706)

These notes should be repeated on the appropriate analysis sheets and cable core plans. The term spare should only be used of equipment, cable cores, or levers where there is no wiring or locking attached.

When a note is no longer applicable at a subsequent stage, it should be crossed out in green.

The appropriate notes should be retained on the maintenance records, when updated (see Part J). Source records should be updated as required in Sections 2.2 and 3.2.

A full issue of installation and testing details and maintenance records, including analysis (see Part N), should be made for each stage in accordance with GK/RT0201.

General requirements for circuit diagrams are given in Part N, Sections 4.11 and 4. I2.





4.2 Other Design Details Signalling plans should show trackside equipment not yet commissioned (and redundant trackside equipment that has been left in situ) with a solid symbol and a note "NOT IN USE", or “C&P”. Not yet installed or recovered trackside equipment, with circuitry in the interlocking, should be shown with a dotted symbol. Identities corresponding with the interlocking should be shown.

Control tables should show the final controls where the circuitry is in the interlocking, but not yet commissioned, (or the original controls where circuitry in situ has been made redundant) with appropriate notes, such as "NOT IN USE", FALSE FED', or TRACK CIRCUITS COMBINED". Redundant controls, where the mechanical locking is left in the interlocking, should be shown similarly, with levers required to be worked to maintain the locking identified with the note “INTERLOCKING LEVER". Where old and new identities are different, a conversion chart should be provided.

Signallers route lists should reflect what the panel or diagram shows.

General requirements for signalling plans, control tables and route lists are given in Part N, Sections 1.2, 3 and 5.4, respectively.


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Part M Arrangement and Presentation General requirements for format and symbols are given in GK/RT0201, as are special requirements for conformity of presentation when existing installations are altered.

I General Arrangement 1.1 Functional Grouping The following groups of design details should be produced:

a) layout plans, schematics and overview documents, generally required to obtain Approval in principle (see Part N, Section 1);

b) control tables (see Part N, Section 3); c) engineering details (see Part N, Section 4); and d) operational and maintenance details (see Part N, Section 5).

Generally group (a) forms part of the design input for group (b) and likewise group (b) for group (c).

1.2 Geographical Grouping Generally, design details should be geographically grouped as follows, so as to facilitate the implementation of GK/RT0010, with separate index sheet(s) for each group (see Part K):

a) Signalling plans divided at interlocking boundaries (where practicable) and signal box boundaries. (An overlap between signal boxes may be necessary to ensure that each plan shows all functions controlled from its respective signal box, up to the approach side of the first caution signal.)

b) Control tables grouped to each interlocking, ground frame, or automatic level crossing.

c) Engineering details grouped to each apparatus housing (or suite of apparatus cases identified as a single lineside location), together with the trackside equipment directly fed and the through circuits described in Section 5.4.

d) Longitudinal details, such as bonding plans and cable plans, divided at interlocking boundaries.

e) Power distribution details grouped to the power supply point

For production purposes only, details for adjacent signal boxes or interlockings may be combined, e.g. as in scheme plan production, provided that the design records are arranged to be divided at the interlocking boundaries defined by the signalling plans

In absolute block areas there may be gaps between signalling plans of adjacent signal boxes. In this case separate signalling plans may be provided for any in-section ground frames or level crossings. These should be cross referenced on the signalling plan of the main signal box.

2 Colour Presentation 2.1 New and Altered works Examples of the red / green colour convention used for production purposes, to identify new / recovered work on production copies of design details, are given in Figures M2 to M5.

The colour convention may be applied to individual drawing elements by either:

a) drafting in colour; b) drafting in black and applying colour shading; or c) CAD colour plotting.





The style of presentation should be consistent. Recoveries may be additionally identified with small green or black crosses. Dotted green should not be used to show recoveries, due to confusion with dotted symbols depicting equipment physically removed but remaining in the interlocking logic (see Part L).

Where a new drawing, or discrete parts of a drawing, depict all new work to be installed, the drawing, or the discrete parts bounded by a red border, should be endorsed in red “ALL NEW WORK”. Where recoveries are such that a complete drawing, or discrete parts of a drawing, become redundant then the drawing should bear a large green cross through the sheet, or through the discrete parts bounded by a green border. This avoids the need to colour each individual element.

Where an existing element is transferred from one drawing to another, both drawings should bear a suitably coloured note to that effect, quoting the relevant sheet numbers. This is to assist traceability in analysis and record production.

The status of each sheet produced (i.e. red, green, combined, new, abolished) should be shown on the index (see Part K).

The use of the colour blue to identify post-construction modifications is described in Part G.

The colouring of not yet commissioned or redundant functions is considered in Part L.

2.2 Special Colour Applications Colours may be used for special purposes on design details, both production and record copies. Where the colours are not otherwise defined, a key should be provided.

In cases of potential confliction with Section 2.1, measures should be taken to prevent confusion. This may require the omission of the special colouring from production copies.

Examples of special colour applications include:

a) to identify track sections, usually blue and yellow alternately on up lines; green and brown / orange alternately on down lines; but abutting track sections should always be given different colours (see also Part N, Section 4.2);

b) to show the actual colour of the product, e.g. road sign profiles, or signalling display systems (coloured in accordance with GK/RT0005);

c) to distinguish dimension lines, location areas and interlocking boundaries, etc. from the drawing details (usually using the colour blue): and

d) to identify the ownership of underground utilities, e.g. on level crossing ground plans.

3 Layout Plan Convention

A layout plan is a single line plan, generally drawn to scale, showing signalling features and identities, and includes:

a) scheme plans (Part N, Section 1.1); b) signalling plans (Part N, Section 1.2); c) stage scheme plans (Part N, Section 1.8), d) location area plans (Part N, Section 4.1); e) map search plans (Part N, Section 4.13.2); f) sub-route and sub-overlap plans (Part N, Section 4.13.3): g) operating notice diagrams (Part N, Section 5.5); and h) safety diagrams (Part N, Section 5.6).


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3.1 Sheet Size Where plans are required to be of greater length than the metric standards, non-standard drawing sizes may be used provided that their height corresponds to the height of one of the standard A sizes and their length is a multiple of 210mm. This ensures that prints of all plans can be folded to A4 size. When folded the title block should be visible.

See GK/RT0201 for conformity of presentation when existing installations are altered.

3.2 Scaling Longitudinal scales should be determined by considering:

a) the extent of the plan (see Section 1.2), b) the sheet size and convenient length (see Section 3.1); c) the degree of congestion using standard size symbols; d) the need to avoid sheet breaks and scale changes in S&C and other complex

areas; e) the need to keep scale changes to a minimum; and

f) the use of standard scales in the range of 1:500 to 1:10000.

Scale changes should be dimensioned and shown as follows. If the whole plan is to the same scale, the scale should be shown in the title block.

1:1000 1:2000

123 456m

Although transverse distances are not generally to scale, standard spacing should be adopted, which should not be less than:

a) distance between adjacent tracks 10mm b) platform width 8mm

Certain plans for convenient use may be drawn not to scale, but geographically correct, e.g. operating notice diagrams.

3.3 Datum Points A datum point should be used to dimension all features on the plan, by showing the appropriate distance adjacent to the feature concerned. In addition, signal to signal distances should generally be given for main stop signals. (Isolated distant and banner repeating signals should be dimensioned to their associated stop signal.) Where a datum or datums are used which give different distances by different routes, this should be made clear on the plan. If a local datum is used, this should be linked to the adjacent ones, e.g. by giving interlocking to signal box distance, or road width for a level crossing. (Box to box distances may not be necessary in non-track circuit block areas.) The datum should generally be:

a) the centre point of the signal box, level crossing or interlocking (but only once the installation has been built; never for a proposed site);

b) the "running on“ edges of the level crossing - two datums (but not for new work);

c) the origin of the mileposts or metric equivalent; or d) some other convenient permanent fixed point

3.4 Units of Measurement The preferred unit of measurement is the metre, although imperial units may be shown where documented in the design specification. Measurements should generally be rounded to the nearest metre or yard. Different conventions of measurement should not be mixed on one plan. The following conversion factors and abbreviations should be used where necessary:





1 kilometre (km) = 1 000 metres (m) 1 yard(yd) = 0.9144m 1 mile (M) = 1 760yds = 80 chains (Ch) 1 Ch = 22yds = 100 links (L)

Speeds should be quoted in the same units as speed restrictions are published in the sectional appendix, e.g. miles per hour.

3.5 Orientation of Plans New layout plans should generally be drawn with the "up" direction towards the left, unless any of the following criteria have a more significant influence:

a) the layout plan would be orientated differently to the signaller's display; or b) adjacent signalling / scheme plans are already orientated differently.

The lowest numbers should be allocated to signals at the "up” end of the layout, as described in GK/RT0009. Lever frames, however, should be arranged with lever one on the left.

The orientation of signaller's displays is described in Part N, Section 5.1.

3.6 Presentation of Not Yet Commissioned or Redundant Functions This subject is considered in Part L.

4 Control Tables Guidance on the format of control tables is given in Part N, Section 3.

4.1 Sheet Size The preferred size for control tables is A3 or A4.

See GK/RT0201 for conformity of presentation when existing installations are altered

4.2 Convention for Control Table Alterations to Assist Testing Where interlocking logic (including circuits or mechanical locking) relating to a particular control is rearranged in connection with some other alteration, but the actual control remains unchanged, such control should generally be identified in the control tables to assist testing. This should be achieved by colouring the control red on the red copy and green on the green copy (or diagonally green and red, when using the one drawing method), without changing the source record.

Note that this generally requires control table colouring to be modified after the engineering details have been designed

However, if the whole interlocking is re-engineered (e.g. EPROMs replaced), only the actual changes (as shown on the data difference lists) should be coloured.

The designer should be careful not to jeopardise the independence of principles testers by advising on the extent of testing necessary, other than by colouring control tables.


Signalling Design:Production Guidance



4.3 Presentation of Not Yet Commissioned or Redundant Functions This subject is considered in Part L.

5 Circuit Diagrams Convention and

NomenclatureThe arrangement of circuit diagrams should generally follow one of these patterns: signal boxes and interlockings (see Part N, Section 4.11); or lineside locations (see Part N, Section 4.12).

Circuit diagrams should fulfil the following purposes, as necessary:

a) material ordering; b) construction and pre- wiring of racking, apparatus cases or relocatable

equipment buildings (REBs); c) site construction; d) commissioning testing; e) producing other design details, such as cable core plans and bonding plans; f) updated for record purposes; g) routine and incident testing; h) facilitating preventative and corrective maintenance; i) correlating actual site wiring to records; and j) alterations to depict proposed signalling work

5.1 Sheet Size The preferred size for circuit diagrams is A3.

See GK/RT0201 for conformity of presentation when existing installations are altered.

5.2 Relay and Circuit Nomenclature GK/RT0205 defines the relay and equipment nomenclature used in this Code of Practice.

Except as shown below, the first cascaded repeat relay should have the letter 'P' inserted before the 'R' in the name. The second and subsequent repeats should have the appropriate number inserted before the 'P'.

Repeat relays of the back contacts of primary relays should be designated PZRs. The designation CR for a simple back contact repeat does not imply the repeating of the primary relay.

Track repeat relays often feature a cascaded slow-to-operate chain to incorporate the time delays explained in GK/RC0752, in order to de-energise each track circuit before the previous one re-energises. So as to ensure that any repeat relay that precedes the primary function relay (see GK/RC0706, Part D), is not used for any other safely-related purpose, a warning note should be added to the contact analysis and, for new work, the letter 'P' should be omitted from the name. The primary function relay should be named 'TPR’. Hence a typical chain might become: TR, T2R, T3R, TPR, T2PR, T3PR, etc. Only the relays indicated in bold should be used for safety-related purposes, such as:

a) controlling automatic signals; b) operating the interlocking; or c) indicating the position of a train to the signaller

Where the letter “Z” (special) is used, the meaning should be explained on the design details, except where the name is in common usage. Common usage relay names incorporating the letter Z are given in Figure Ml. Relay names should convey the function of the circuit, for clarity of identification, to eliminate misunderstanding and to assist maintainers,

Relay Name Meaning Circuit or Usage

Interlocking Systems







ALZR Approach Lock Summation Relay TORR 6W67 Approach Lock Release Relay Approaching locking GEC APZR Pre-Set Exit Relay Pre-Set Shunt SGE/GEC BTZSR Berth Track and Replacement Proving Stick Relay EXIt Sets (not for new work) SGE CUPZR Point Calling Back Repeating Relay Swinging Overlap SW67 DZR Illegal Destination Relay PBI Ring WBS/SW67 FZR Flashing Entrance Relay Output buffer ERSE GCZR Signal Stick Relay Signal Sets AGS/GEC (GF)...ZR Ground Frame Control Relays Power operated ground frame: normal / reverse halves of

mag-stick relay E10k

Signal Proving Relay Signal ahead proving: lamp or controls RT GZR Signal Ready to Clear Relay Aspect controls RT Signal Route Setting Relay Output buffer ERSE LZR Overlap Route Locking Relay Point Sets: Route Locking Level AEI-GRS MXZR Main Exit Delayed Release Relay Common Control Set AGS/GEC NCUPZR Normal Point Calling Back Repeating Relay Swinging overlaps SW67 NKLZPR Norrnal Detection and Locking Proving Relay Points Set WBS NPZR Normal Proving Ring Relay Common Control Set - free-wired GEC NSZR Emergency Replacement Stick Relay Pre-Set Shunt GEC NWZ/LKR Points Controlled Normal or Free & Not Called Relay Panel E10k NWZR Self Restoring Points Relay Points Set ScR NZLPR Locked Normal or Free Repeating Relay Point conditions in route setting WBS/SW67, ScR NZR Normal Points Calling Relay Output buffer ERSE OCZR Swinging Overlap Proving Relay Swinging overlaps SW67 PGZR Repeating Signal Proving Relay Banner repeating signal SW67 ...PZR ... Back Repeating Relays (of primary function relay) General: (formerly ...ZR in some systems)

Non-safety back repeaters may be designated ...CR SW67, E10k, RT

RCUPZR Reverse Point Calling Back Repeating Relay Swinging overlaps SW67 RKLZPR Reverse Detection and Locking Proving Relay Points Set WBS RNZR Main/Pre-Set Exit Relay Pre-Set Shunt GEC RWZ/LKR Points Controlled Reverse or Free & Not Called Relay Panel E10k RZLPR Locked Reverse or Free Repeating Relay Point conditions in route setting WBS/SW67, ScR RZR Reverse Points Calling Relay Output buffer ERSE Reverse Relay emergency release Emergency ground frame SR SUZSR Stepping Up Overlap Release Stick Relay Warner routes SW67 SZR Directional Sticks Reset Priming Relay AHBC RT TZJR Track Sticks Timed Reset Relay AHBC RT TZR Approach Tracks Summation Relay TORR SW67 Track Occupied Relay Axle counters RT, E10k TZSJR Full Strike-in Track Stick Timed Reset Relay AHBC with signal regulation RT TZSR Full Strike-in Track Stick Relay AHBC with Signal regulation RT Train Reached Points Tracks Stick Relay Self restoration of points SW67 UFZPR Any Route Finished Repeating Relay Exit Set WBS USZR 0pposing Route Set Relay Pre-Set Signal Set WBS UZ (O) R Route Track Override Relay Track override buttons (not for new work) E10k ....UZR Route Priming Relays Track Sets WBS WCZR Points Out of Correspondence Relay Points Set AEI-GRS ScR WTZSR Points Reverse Track Stick Relay Self restoration of points - free-wired WBS WZCR Points Called Relay Point control: anti- preselection E10k WZKR Points Out of Correspondence Indication Relay Panel indications ScR WZR Points Free Relay Point calling WBS/SW67 Points Swinging Relay Aspect Level: Swinging overlaps SGE/AGS/GEC ...WZR Point Control Relays Point control: normal / reverse halves of mag-stick relay E10k XLZR Opposing Locking Bypass Relay 0pposing locking omitted - free-wired WBS Z... Block Blocks systems E10k ZCR 0pposing Locking Free Proving Relay Signal Sets AGS/GEC

Figure M1 Common Usage of “Z” Nomenclature continued ...


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ZCSR Door Open Proving Stick relay AHBC: manual control RT ZDR Time of Clearance Controls for Green Relay Tunnel controls RT ZGECPR Overridable Signal Lamp Proving Repeating Relay Single line working E10k Warner Route Signal Relay Warner routes SW67 ZGR Signal Delayed Clearance Relay TOWS SW67 Pre-Setting Signal Relay Main Signal control E10k ZHHPR Double Yellow Proving Repeating Relay Advance warning of divergence: splitting distant signal SW67 ZHPR Route and Yellow Repeating Relay Advance warning of divergence: junction signal SW67 ZHR Time of Clearance Controls for Yellow Relay Tunnel controls RT ZJR Route Setting Premature Release Relay Common Control Set - free-wired GEC ZLR Route Locking Delay Relay Route setting for non- preferred routes SW67 ZNPR Override Switch Repeating Relay Single line working E10k Summation of 0pposing Routes Repeating Relay Panel: for common exits E10k Pre-Set Signal Relay Pre-set signal control SGE, AEI-GRS,

E10k ZR Anti-Preselection Override Relay Common Control Set - free-wired GEC Main Filament / Power Off Proving Relay Colour Iight signals without secure power supply E10k Override Route Relay Override E10k ZRELR Sub Overlap Release Relay Special Locking Unit SGE/AGS/GEC Z(SL)R Sub Overlap Selection Level Relay Special Locking Unit SGE/AGS/GEC Splitting Distant Proving Stick Relay Advance warning of divergence: junction signal SW67 Anti-Stepping Down Stick Relay Calling on aspect E10k ZSR Pre-set Maintaining Stick Relay Panel E10k Signal Ahead On-Proving Stick Relay Sequential locking E10k Override Stick Relay Single line working E10k ZTPR Directional Approach Tracks Summation Repeating Relay TOWS SW67 Block Clear Repeating Relay WR tokenless block or bi-directional signalling E10k ZTUYR Sequential Track Proving Route Disengaging Relay TOWS SW67 ZUCR Full/Restricted Overlap Route Proving Relay Stepping up E10k ZUGR Pre-Set Route Signal Relay Route indicator control with more than one pre-set route E10k ZULSR Pre-Set Route Locking Stick Relay Route stick E10k ZUPZ (n) R Summation of Route Back Repeaters Relay Panel: 'n' indicates the number of parallel repeaters E10k ZUR Overlap Route Setting Relay Point Sets: Completion Level AEI-GRS ZWJR Points Restoration Timing Relay Self restoration of Points E10k ZWR Ground Frame Points Release Relay Ground frames E10k ZXLR Sub Overlap Exit Locking Relay Special Locking Unit SGE/AGS/GEC ZXR Approach Tracks Summation Audible Warning Relay TOWS SW67 Subsidiary Exit Relay Exit Sets: Locking Level SGE/GEC

AHBC = Automatic Half Barrier Crossing ERSE = Electronic Route Setting Equipment PBI = Push Button Interlocking TORR = Train Operated Route Release TOWS = Train Operated Warning System See References for interlocking systems.

Figure Ml Common Usage of "Z" Nomenclature

Unique circuit names, based on the relay or equipment name, should be shown in full on circuit diagram wiring sheets (on the outgoing side of cable terminations), cable termination sheets and core plans. Return conductors should be identified with a suffix 'N' or 'NX'; polarised circuit conductors by the suffixes (1) and (2); supply conductors by the suffixes (B) and (N), or (BX) and (NX); and intermediate portions, where applicable, by suffixes (1), (2), (3), etc. Where necessary to uniquely define functions, signal box, or other; prefixes may also be used.

For nomenclature of wires, see Section 6. 1

5.3 Nomenclature in Electronic Systems GK/RT0205 nomenclature should be used, wherever practicable, to uniquely define logic elements, transmission channels and input / output functions in electronic systems. Names similar to the circuit names described in Section 5.2





may be suitable, but the letter ‘R' should be omitted if there is no relay associated with the data.

Identities of transmission channels and input / output functions should be tabulated on analysis or allocation sheets and shown on the corresponding wiring sheets.

Filenames should be compatible with the nomenclature used.

5.4 Through Circuits and Duplicate Representations An external circuit drawn in entirety from supply to destination is known as a through circuit. All external circuits should be drawn as through circuits in at least one place, in accordance with GK/RT0205, in order to assist testers and maintainers. Through circuits should show relay contacts, equipment and disconnection points at the remote sites, but not contact, fuse, or terminal allocations.

The convention on circuit diagrams is for every wire to be shown once, and only once, by the use of a solid line. If it is necessary to show a wire or a circuit more than once, e.g. as a through circuit, the subsequent circuit should be depicted with a dashed line.

5.5 Typical Circuit Representations No new design should be produced in the form of a typical circuit drawing, i.e. a circuit diagram which applies to a number of installations or functions. All new circuits should be drawn out in full except those relating to the internal wiring of a pre-wired unit. Where a typical circuit (see References) is used as a basis for design, it should be customised for each application and the unique circuit details and names added.

5.6 Internal Wiring Full internal wiring of pre-wired units should be provided where this information is necessary for the designer, installer, or maintainer. Simplified, or partial, internal wiring may be provided for sealed units. Where terminals of units are used in different circuits that appear on more than one wiring sheet, terminal analysis should be provided. Pre-wired units include:

a) trackside equipment, such as signal heads and point mechanisms; b) other equipment to which maintainers have access; c) geographical relay sets; and d) other sealed units, such as timers, which form part of a relay circuit

If there is insufficient space on circuit diagrams, the internal wiring may be shown on a separate reference sheet provided in each location and interlocking where the equipment is used (see Part N, Section 4.11.2). The connection terminal numbers and the appropriate reference sheet number should be shown on the circuit diagrams for each application.

5.7 Convention for Wiring Alterations Examples of the red / green presentation used to identify new / recovered wiring are given in Figures M2 to M5.


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Figure M2 Colour Convention for Alterations to Existing Circuits - One Drawing Method

Note: No pulling back and re-use of existing wires to be assumed, except on same item of equipment (see Figure M3).

(a) Contact of New Relay Used in Existing Circuit

(b) Spare Contact of Existing Relay Used in Existing Circuit

(c) Contact of Existing Relay Recovered from Existing Circuit: Relay Remains - Contact Spare

(d) Contact of Existing Relay Recovered from Existing Circuit: Relay also Recovered

(e) Contact of Existing Relay Recovered from Existing Circuit:

AND Contact Re-Used in Existing Circuit

OR Contact Re-Used in New Circuit

(f) Relay Nomenclature Change

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2B TPR

R1 R2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2B TPR

R1 R2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

ETPR

A1 A2

BTPR

A1 A2

DTPR

A1 A2

B CTPR

A1 A2B C TPRR1 R2





Figure M3 Colour Convention for Alterations to Existing Circuits - One Drawing Method

(a) Relay Configuration Change - Existing Connectors Re-Used

(b) Relay Configuration Change - New Connectors Required

(c) Relay Contact Recovered from Existing Circuit: Two Wire Connector

(d) Relay Contact Recovered from Existing Circuit: Second Wire with Two Wire Connector at Both Ends

(e) Addition of Relay Contact: Two Wire Connector

(f) Addition of Relay Contact: Second Wire with Two Wire Connector at Both Ends

B TPRR1 R2

BTPR

A1 A2

B TPRR1 R2

R3

BTPR

C1 A1 A2 C2

ATPR

A1 A2

CTPR

A1 A2D

TPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2D

TPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2D

TPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2D

TPR

A1 A2

BTPR

A1 A2


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(a) Contact of New Relay Used in Existing Circuit

(b) Spare Contact of Existing Relay Used in Existing Circuit

(c) Contact of Existing Relay Recovered from Existing Circuit: Relay Remains - Contact Spare

(d) Contact of Existing Relay Recovered from Existing Circuit: Relay also Recovered

(e) Contact of Existing Relay Recovered from Existing Circuit:

AND Contact Re-Used in Existing Circuit

OR Contact Re-Used in New Circuit

(f) Relay Nomenclature ChangeGREEN COPY (G) RED COPY (R)

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2B TPR

R1 R2

ETPR

A1 A2

BTPR

A1 A2

DTPR

A1 A2

B TPRR1 R2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

ETPR

A1 A2

BTPR

A1 A2

DTPR

A1 A2

ETPR

A1 A2

DTPR

A1 A2

BTPR

A1 A2B TPR

R1 R2

CTPR

A1 A2C TPR

R1 R2

NOW B TPR WAS C TPR

Figure M4 Colour Convention for Alterations to Existing Circuits - Two Drawing Method

Note: No pulling back and re-use of existing wires to be assumed, except on same item of equipment (see Figure M5).





(a) Relay Configuration Change - Existing Connectors Re-Used

(b) Relay Configuration Change - New Connectors Required

(c) Relay Contact Recovered from Existing Circuit: Two Wire

B TPRR1 R2

BTPR

A1 A2B TPR

R1 R2

BTPR

A1 A2

B TPRR1 R3

BTPR

C1 C2B TPR

R1 R2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

DTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2D

TPR

A1 A2

BTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2B

TPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2

DTPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2B

TPR

A1 A2

ATPR

A1 A2

CTPR

A1 A2B

TPR

A1 A2

DTPR

A1 A2

(d) Relay Contact Recovered from Existing Circuit: Second Wire with Two Wire Connector at Both Ends

(e) Additional of Relay Contact: Two Wire Connector

(f) Addition of Relay Contact: Second Wire with Two Wire Connector at Both Ends

GREEN COPY (G) RED COPY (R)

Figure M5 Colour Convention for Alterations to Existing Circuits - Two Drawing Method


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All wires to be recovered should be shown to be removed in their entirety. Wires are only coloured as re-terminated when they originate from the same item of equipment (see Figures M3 and M5). Other pulling back and re-termination of wires should not be assumed in the design. Spare terminals and fuses should be shown in situ on circuit diagram layouts and analysis.

Where an existing wire is to be removed from an existing crimped or soldered connector containing two wires, e.g. a relay spade, the remaining wire should generally be coloured as a new wire (see Figures M3 and M5, item (c)). Similarly, where a new wire is to be added to an existing connector containing one wire, the existing wire should generally be coloured as a new wire (item (e)). However, where the other end of the remaining wire is likewise terminated on a connector with two wires, the wire should not be coloured and it should be assumed that it will be retained (items (d) and (f)). This is to encourage best practice during a controlled changeover.

5.8 Complex Alterations It is important, so as not to create a hazard for the unwary, that complex or geographical circuitry is altered in a consistent manner, in accordance with the original design standards.

The design documentation should be quoted on the reference sheet at the front of the circuit diagrams (see Part N, Section 4.11.2). Where full design explanation documentation is not available, the level of design competence required should be an appropriate degree higher.

Guidance on geographical circuitry is given in GK/RC0706, Appendix F3. Similar occurrences of the required controls should also be studied to ensure consistency.

5.9 Presentation of Not Yet Commissioned or Redundant Circuitry This subject is considered in Part L.

6 Nomenclature for Cables, Wires and

Terminations 6.1 Circuit Diagrams The size, type and colour of wires should be shown on circuit diagrams. See GK/RT0205 for colour abbreviations. To reduce congestion, default attributes may be omitted. Preferred examples include:

a) single wires as 0. 75mm2, black, for conventional circuits and 0. 75mm2, white, for wiring to DEF STAN 61-12;

b) types as Al for 0. 75mm2 and 1. 15mm2, and 81 for the larger sized wires; c) colours as black or white; and d) fuses as BS 714, 3A, for conventional circuits.

The default cable and fuse types and ratings should be defined on the reference sheet at the front of each set of diagrams (see Part N, Section 4.11.2). Other cable types may be indicated by notes (preferably #1, #2, #3, etc.) that are explained on the sheet(s) on which they are used.

Connections to items of equipment should quote the unique terminal marking on the equipment itself.

6.2 Main Multicore Cables and Power Cables Main cable names should include the identities of the locations in which each end of the cable is terminated, suffixed with a sequential number or letter if there is more than one cable between the same locations.



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The cable size, number of cores, specification and type of cable, and unique cable identification name should generally be shown in full on circuit diagram cable termination sheets (Part N, Section 4.11.13), and cable schematic (Part N, Section 4.5) and core plans (Part N, Section 4.6).

6.3 Tail Cables Tail cable names should follow the standard nomenclature given in GK/RT0205 for the item of equipment concerned.

The cable size, number of cores, specification and type of cable, and unique cable identification name should generally be shown only within the details for lineside locations (see Part N, Section 4.12).

For track circuit and bonding cable nomenclature, see Part N, Section 4.2.

6.4 Cable Terminations For cable termination analysis, each column should be allocated a consecutive alphabetic identity. Generally the extreme left hand column in an equipment room, or suite of apparatus cases, is referenced A'. The reference of the first link is thus ‘A1'. This reference should be quoted on circuit diagram wiring sheets (below the link symbol) as well as on the cable termination sheets. Links are generally drawn correctly orientated, but, if shown in reverse orientation, they should be headed 'R L'. The extreme right hand column(s) in an apparatus housing, or suite of apparatus cases may be referenced 'T’ and reserved for operational telecommunication cables.

Plug couplers should be similarly analysed and identified on wiring sheets with the plug coupler name and pin number

Further guidance on cable terminations is given in Part N, Section 4.11.13.

6.5 Convention for Alterations Terminals and fuses made spare by alterations should generally be left in situ. This should be indicated on the analysis by colouring green the function name, number of wires, sheet number and, where applicable, fuse rating. The word 'SPARE' or 'SP' should be added in red. See Part J for the treatment of spare items when updating records.

Where items are to be completely removed, the entire analysis should be coloured green.

See Part L for not yet commissioned or redundant equipment

7 Recording of Equipment Specification

To ensure that new signalling systems are comprised only of sub-systems and equipment approved in accordance with GK/RT0104, and to enable them to be managed to ensure continued conformance with the specification, approval and application criteria for their whole life-cycle in accordance with GK/RT0170, the sub-systems and equipment should be uniquely specified in the design details, together with any ancillary information necessary to define the application criteria.

A specification change will also warn of potential problems, or circuit changes necessary.

Any novel use of equipment to fulfil a different purpose from that intended by the manufacturer should also be stated, as well as any use outside of the environment specified by the manufacturer In these cases, and in the case of any other hidden danger to personnel it is necessary to give a specific warning on the design details and quote the product specific, or generic standard by which the equipment conforms to the EMC protection requirements.

The specification should include the following items, as applicable:


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a) equipment type, style, specification number, drawing number or Approval identification (or catalogue number, but only where there is no other means of unique specification);

b) modification state or specification version;

c) coding configuration;

d) voltage rating and / or maximum power consumption;

e) the size and weight of rack mounted equipment (see GK/RC0706, Part G);

f) earthing arrangements, or other precautions necessary under the Electricity at Work Regulations 1989, e.g. shrouding of terminals (see GK/RC0706, Part D);

g) all warning signs, particularly those necessary under the Provision and Use of Work Equipment Regulations 1992 or the Health and Safety (Safety Signs and Signals) Regulations 1996 (see GK/RC0706, Part D);

h) details of any adjustments to be made on site, special construction instructions, or special maintenance requirements, including reference to any operation and maintenance manuals (see Part N, Section 5),

i) additional safety information to enable a competent contractor to put appropriate precautions in place under the Construction (Design and Management) Regulations 1994, including personal protective equipment and warning devices (see Part Q);

j) the approved environment for use, including equipment proximity, climatic, corrosive, or explosive conditions, considering the likelihood and impact of hazards, such as flooding or sea water spray, the degree of dust and water protection required; also environmental nuisance, e.g. specifying acoustic jackets for TI 21 tuning units in residential areas; and

k) other precautions, limitations or constraints on use, such as those imposed by the manufacturer in connection with Conformité Européene (CE) marking and other interface compatibility constraints, or reference to such criteria (see GK/RC0706, Part D).

Designers should ensure the correct choice of equipment to cover the last two items.

This information should be provided on the reference sheet (Part N, Section 4.11.2), circuit diagram, equipment rack layout (Part N, Section 4.11.4), or by reference to standard equipment drawings or specifications, or to the design specification or health and safety file (see GK/RT0201). However; circuit diagrams and rack layouts should not be overloaded with confusing information. Ancillary information that is not required for the lifetime of the installation may be omitted from design details, if persons requiring it are informed by other means.

8 Analysis 8.1 Provision of Analysis Where terminals of components are used in different circuits that appear on more than one wiring sheet, terminal analysis should be provided. Relay contact analysis should be provided for all relays, and other units fitting a BR829 plugboard. Electronic system allocations should be provided as described in Section 5.3. The presentation should be such that the designer, correlator, installer and maintainer are given unambiguous and concise information in a compact form.

Analysis should generally be associated with circuit diagrams, as follows:

a) signal boxes and interlockings - see Part N, Section 4.11; b) lineside locations - see Part N, Section 4.12.



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8.2 Convention for Analysis Alterations Where a wire to a terminal is changed, but the number of wires remains the same, this should be indicated by colouring the number red on the red copy and green on the green copy (or diagonally green and red, when using the one drawing method), without changing the source record.

When issued in connection with wiring alterations, or correlation, circuit diagrams should be accompanied by the appropriate analysis. Where documented in the design specification, analysis may be produced by the two drawing method, but omitting the green copy.

When undertaking alterations at an installation without full analysis, the scope of analysis provision should be documented in the design specification.

8.3 Warning Notes The following warning notes should be added to analysis sheets, as appropriate:

a) relay contacts not to be used for safety-related purposes (see Section 5.2); b) notes for temporary work (see Part L, Section 4); c) cable termination notes (see Part N, Section 4.11.13); and d) any other warning necessary to ensure the safety of personnel.


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Part N Minimum Requirements for Design Details The minimum requirements for each specific type of documentation are as listed below. The examples shown in Figures N1 and N4 to N17 are typical and should not be taken to imply any particular requirement

I Documentation Required for Approval

in Principle The details required to be submitted for approval in principle, in accordance with GK/RT0201, include the scheme plan and associated documentation.

1.1 Scheme Plan A scheme plan is a scale layout plan depicting new or altered signalling systems. Where sequential commissionings are required, derivative stage scheme plans should be produced (see Section 1.8).

A scheme plan is produced to express, in a form that is readily understood by signal engineering and operations personnel, the signalling requirements of all interested parties. Railtrack should have procedures in place to control the interfaces between disciplines.

Scheme plans should fulfil the following purposes, as necessary:

a) submission for approval in principle and Her Majesty's Railway Inspectorate (HMRI) statutory approval as described in GK/RT0201;

b) checking interdisciplinary details associated with train operating, permanent way, civil engineering, electric traction, plant and telecommunication requirements;

c) estimating and contract tendering, where applicable;

d) compiling control tables, and other design details;

e) providing a derivative for the production of a location area plan (see Section 4 1);

f) deriving signal box diagrams, panel faceplates, VDU maps, fixed diagrams and maintainer's monitoring panel face plates for remote interlockings (see Section 5.I);

g) creating the simplified layout plans required for automatic route setting; map search, sub-route and sub-overlap plans (see Section 4.13); operating notice diagrams (see Section 5.5); and safety diagrams (see Section 5.6); etc;

h) signal sighting (see Section 1.9);

i) laying out new equipment on site and identifying recoveries (this is also shown on the location area plan, when available, with more engineering detail);

j) functional and control table testing;

k) compiling specifications of work for the fringe areas;

l) in the case of multiple stage schemes, deriving stage scheme plans for each commissioning (see Section 1.8);

m) producing a signalling plan for record purposes (see Section 1.2); and



1 0 4 R A I L T R A C K


n) other purposes as necessary.

The infrastructure controller's specific requirements should be obtained from the outline project specification (OPS) and associated documentation. All details listed in Sections 1.1.4 to 1.1.7 should be shown on the plan and, where practicable, dimensioned to the datum point. Items that are marked* should always be so dimensioned.

Part of a typical scheme plan (for part of the layout in Figure R12) is illustrated in Figure N1. See Part M, Section 3 for layout plan convention.

1.1.1 Scheme Plan Layout The scheme plan should be laid out in four parts, viz:

a) The single line plan of signalling, drawn to scale longitudinally, which should include items shown in Sections 1.1.4 to 1.1.7.

b) The site plan, showing the geographical location of the scheme within the railway network.

c) General notes applicable to the signalling scheme as a whole should be included next. In addition, the signal box notes for a new signal box should be included in full, either here, beside the signal box symbol or referenced and provided as a separate document. For signal box and general notes see Section 1.3.

d) An approval and version panel explained in Part K, forms the final leaf

A typical layout is illustrated in Figure N2.

1.1.2 Fringe Areas The fringe areas of the scheme may be drawn not to scale. Only relevant signalling belonging to a fringe signal box need be shown, but all fringe signalling functions that it may be necessary to show in the associated control tables should be included.

1.1.3 Associated Information The following ancillary information should also be provided, either on the scheme plan, or as separate documents and referenced on the scheme plan:

• signal box notes (Section 1.3); • numbering grid (Section. 1.4); • signal spacing parameters (Section 1.5); • aspect sequence chart (Section 1.6); and • table of signal routes (Section 1.7).

Scheme plans generally have four phases of production, as described in Sections 1.1.4 to 1.1.7.


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Figure N1 Extract of Typical Scheme Plan



1 0 6 R A I L T R A C K


Figure N2 Typical Scheme Plan Layout

APPROVAL AND VERSION PANEL

SEE FIGURE K4

GENERAL NOTES

SEE SECTION 1.3

SITEPLAN

SIGNALLING

PLAN

210mm


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1.1.4 Civil Engineering Features The base plan should include the following;

a) gradient posts* ;

b) ¼ mileposts (or metric equivalent)*;

c) mileage changes*;

d) the main route lines (generally shown straight);

e) the permissible speed, including changes in speed* and turnout speeds (see GK/RT0007 for any proposed alterations);

f) geographical names (see GK/RT0009);

g) the accurate position of S&C (drawn in their normal lie);

h) any additional trap points or derailers required (see GK/RT0078);

i) viaducts and tunnels (with lengths);

j) bridges that effect the positioning of infrastructure* (ensuring that essential detail is not obscured) - see Section 5.1.1 for information to be supplied to the signaller;

k) station and other platforms (numbered if relevant to signalling);

l) level crossings* (including all vehicular crossings and all other crossings with some form of protection) - see Section 5.1.1 for information to be supplied to the signaller;

m) buffer stops*;

n) traction substations* and, in d.c. traction areas, track paralleling (TP) huts* (neutral sections should be shown in a.c areas with a special symbol to restrict the placing of signals in accordance with GK/RT0037);

o) limits of electrification;

p) other adjacent railway, electric tramway, or high voltage overhead power line to highlight potential signal sighting, immunisation or track circuit problems (this also applies to railways and tramways crossing by bridge or tunnel);

q) site access points (both foot and vehicular);

r) when sited, signal boxes* (with name and prefix), interlockings* and ground frames*; and

s) reference at the extremities to any continuation sheet*.

Note: * These items should always be dimensioned to the datum point.

1.1.5 Main Running Signals The following features associated with main running signals (and stop boards on running lines) should be added:

a) positioning* (see GK/RT0034 and GK/RT0035);

b) aspect sequence details (unless given elsewhere, see Section 1.6);

c) signal identities (see GK/RT0009) signal designations (showing normal aspect);



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d) standard signal profiles (see GK/RT0031) - these are subject to signal sighting (Section 1.9) and mechanical design (Section 4.10);

e) table of signal routes, once signals have been numbered (unless given elsewhere, see Section 1.7); and

f) key track section joints (defining overlaps, clearance points and standage, etc.).


Where appropriate reference to “signals" should be understood in relation to movement authorities within both lineside signalling and cab signalling systems.

Guidance on the positioning of running signals is given in GK/RC0706, Part S.

1.1.6 General Signalling Details The remaining details should be added as follows:

(a) Other signals and indicators (see GK/RT0031), including:

i) position light signals; ii) other subsidiary or shunting signals; iii) route indicators; iv) fixed red stop signals*; v) exit signals from non-running lines*; vi) loading / unloading indicators; vii) limit of shunt signals; viii) stop boards (stating the legend); ix) shunter's white lights; driver’s crossing indicators and advance warning

boards; and x) distant boards* permissible speed indicators and advance warning

indicators, together with any associated permanent automatic warning system (AWS) inductors (see GK/RT0038).

(b) Other facilities for signals, including:

i) AWS inductor - simple (permanent and electro), bi-directional, directional / selective (i.e. suppressed), or permanent (see GK/RT0016); or other protection system devices, e.g. TPWS loops;

ii) signal post telephone (SPT) showing the signal box prefix letters (or covered by a general note) and any diamond signs, etc. (see (e)viii));

iii) floodlights: for stop / warning boards (unless reflectorised and trains equipped with headlights), disc signals (in colour light areas) and tunnel telephones;

i. automatic working or replacement facilities and signals controlled by a gate box, but with telephone to the supervising signal box (or shown on the table of signal routes);

ii. single device controlled signals protecting a.c. neutral sections, etc, identified with a note;

iii. signal replacement track section joint, dimensioned if between 0m and 5.5m beyond the signal, and last wheel replacement facility;

iv. limit of overlap track section - for full overlaps, restricted overlaps (ROL), and / or phantom overlaps (POL), including bi-directional overlap joints;

v. alternative limits of overlap afforded by swinging the overlap at facing “hinge” points;

vi. facilities for selecting alternative routes, or overlaps;


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vii. automatic train protection (ATP), or train protection and warning system (TPWS) loops or balises (see GK/RT0015);

viii. train stops (see GK//RT0017);

ix. lever lock or block release symbols;

x. for specified pairs of opposing position light signals, the legend: "Opposing Locking Omitted” with an arrow to each; and

xi. signal passed at danger (SPAD) mitigation facilities, including SPAD indicators and / or selective AWS inductors (see GK/RT0078). (Note that the abbreviation SPAD is non-preferred for a SPAD indicator, due to potential confusion with inductor.)

c) Points, including:

i. method of operation, or by general note (where applicable, the point machine symbol should be shown on the side with the best provision for personnel safety, usually the cess or ten foot side). Point mechanism symbols may alternatively be shown on the bonding plan, particularly in d.c. traction areas where the conductor rail is required to be gapped.

ii. symbol for an independent facing point lock;

iii. crank or pump handle location;

iv. point zone (PZ) telephones;

v. split detection (covered by a note) or separate end numbering;

vi. electrical detection for mechanically operated points;

vii. point switch heaters (usually covered by general note);

viii. switch diamonds (treated as two point ends) or swing nose crossings;

ix. scotch blocks or derailers;

x. facing trap points, with sand drag if necessary (sea GK/RT0078), or run back spring controlled catch points;

xi. self restoration of power operated trap points, derailers, or catch points (covered by a separate note); and

xii. points which are clipped and padlocked out of use pending abolition or pending commissioning.

d) Train detection or block system, including:

i. each track circuit or axle counter section extremity using the standard symbols;

ii. clearance points (dimensioned from the fouling point) and track sections less than the minimum length which thus require special controls (stating the length) (see GK/RT0011);

iii) track circuit interrupters on trap points or catch points;

iv) track sections at in-section ground frames;

v) additional track sections for the approach release of junction signals or warning / position light aspects (see GK/RT0035), or to control an AWS inductor and / or replace a banner signal on a permissive line;



1 1 0 R A I L T R A C K


vi) the final track section joint at the extremity of an area of continuous train detection;

vii) miscellaneous treadles;

viii) stainless steel welded strips on lightly used crossovers or lines;

ix) additional track section joints for immunisation purposes or to protect dangerous goods facilities (see electric traction standards);

x) limits of track sections indicated in each signal box;

xi) track sections or train approaching indications that are combined on the signalling display, defined by a note on the plan, stating the constituent track sections and any point or signal conditions;

xii) track sections that are divided for operating purposes, but indicated as one to the signaller;

xiii) symbols depicting block instruments, adjacent to the signal box symbol (or covered in the signal box notes); and

xiv) track circuit actuator interference detector (TCAID) devices.

(e) Additional information in areas of semaphore signalling, or manual block (sea GK/RT0039) including:

i) symbol for power operated semaphore signals;

ii) slot symbol for any signal worked from more than one signal box, such as a home signal combined with the starter for the box in rear; but not shown for a distant arm on the same post as a stop signal, unless (e.g. in the case of an outer distant) it is also slotted by another signal

iii) multiple signals to convey routing information;

iv) intermediate block home and distant signals (generally colour light and worked by the same lever) to improve headway, with any associated warning of train running away covered by a note;

v) a block release symbol on the section signal (or intermediate block home) that controls entry into the block section ahead;

vi) a track section for the berth of the home signal and elsewhere where the line is not clearly visible to the signaller;

vii) clearing points or block overlaps defined by track section joints identified as “BOL";

viii) a diamond sign for signals with berth track sections (or other means of detection, such as train waiting treadle or electric token working), but no telephone;

ix) treadle operated annunciators or train waiting indications covered by notes;

x) a bell symbol and note for older types of crossing or train activated warning system;

xi) multiple signals worked by the same lever identified by a note arrowed to the signals and stating any selection by points;

xii) signal repeaters denoted by letters on the plan, or listed in the signal box notes (not required for colour light aspects repeated);


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xiii) symbols for intensified light, or electrically lit semaphores, or retroreflective arms covered by a note; and

xiv) special arrangements of mechanical detection covered by notes.

(f) Ground frames (only where specified), including symbol for type of ground frame, number of functions and whether covered, with additional information adjacent:

i) ground frame name;

ii) dimension to the datum point*;

iii) release lever / switch number and the prefix and release number of the main signal box (if there is more than one release, each release should indicate the function concerned with an arrow);

iv) symbol for the telephone to the main signal box;

v) a slot symbol for any ground frame signals which either require a separate release from the main signal box, or have some routes controlled from the ground frame and some from the main signal box (with a suitable note in the relevant route boxes); and

vi) the ground frame notes (see Section 1.3).

(g) Level crossings (see GK/RT0070), including symbols for type of protection (number and type of barriers, road lights, miniature stop lights, staff crossing white lights, etc.), with additional information adjacent:

i) legal name; dimension to the datum point*;

ii) type of control (AHBC, AOCL, etc.);

iii) symbols for telephones to the supervising or monitoring signal box (with prefix);

iv) a note if an automatic raise or automatic lower facility is provided for MCBs;

v) advance warning boards* and, where applicable, stop boards for OCs and TMOs;

vi) symbols for the drivers' crossing indicators and crossing floodlights for AOCLs and ABCLs;

vii) symbols for the level crossing advance warning boards* and AWS inductors for AOCLs and ABCLs, with cancelling indicators where necessary on bi-directional lines;

viii) symbols for the special speed restriction boards* for AOCLs & ABCLs, and wrong direction speed restriction boards*, where applicable, for all automatic crossings;

ix) delineations indicating the strike-in points* for automatic crossings, stating the travelling time to the crossing at the stated permitted approach speed (or the appropriate reduced speed for AOCLs and ABCLs);

x) inner strike-in points*, similarly, where required for an intervening station or signal, with the criteria used to calculate the attainable speed;



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xi) where not all trains stop at an intervening station, a note of stopping / non-stopping selection;

xii) run-by treadles or track circuits at any intervening signal (intervening automatic signals generally display a red aspect);

xiii) exit track circuit joints and treadles;

xiv) shod track sections over the crossing;

xv) delineations indicating the train detection device* which initiates automatic lower and picture switching for CCTV crossings; and

xvi) for automatic crossings, the level crossing notes (see Section 1.3).

Note that items (g) vi) to ix) are also required on wrong line approach tracks unless bi-directional controls are specifically excluded.

See GK/RT0033 for details of signs. Guidance on level crossing design is given in GK/RC0706, Part X.

(h) Miscellaneous facilities, including:

i) train ready to start (TRTS) plungers, on platforms where passenger services commence;

ii) right away (RA) and close doors (CD) indicators and plungers on driver only operation (DOO) lines;

iii) alias plates and radio channel change markers for cab secure radio (CSR) or radio electronic token block (RETB);

iv) off indicators, for the use of operating personnel (see GK/RT0031);

v) shunter's acceptance devices or releases, provided where a shunter has no other release on incoming routes;

vi) train arrived complete plungers, where the signaller cannot sight the tail lamp of a train leaving a block section (unless a tail lamp telephone or CCTV system is provided);

vii) lockout devices* for personnel safety on bi-directional or depot lines, showing the number of the signal box release, and the direction locked out, where applicable (see GK/RT0030);

viii) train activated warning systems, with the extent of the zones indicated (see GK/RT0029);

ix) buffer stop lights (see GK/RT0031));

x) hot axle box detectors;

xi) AWS test inductors or tripcock testers;

xii) other telephones at strategic points, such as tunnel mouths;

xiii) other numbering or identification necessary (see GK/RT0009); and

xiv) various delineations, such as limits of contract, limits of signalling alterations and areas of overlap with other signalling / scheme plans.



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1.1.7 Site Survey Amendments The plan should be amended to signal sighting (see GK/RT0037) or site survey requirements:

a) amendments to signal positions* recommended by the sighting committee (subject to compliance with GK/RT0034 and GK/RT0035);

b) recommended amendments to profiles, with appropriate symbols for cantilevers, gantries and wall, roof, or ground mountings (subject to compliance with GK/RT0031);

c) banner repeating signals*, co-acting signals* or off indicators recommended;

d) recommended orientation of the SPT with any special facilities for restricted clearances or illumination;

e) symbols for intensified light, or electrically lit semaphores and arm repeaters, or retroreflective arms covered by a note, where recommended;

f) requirement for short range optical systems, or spreadlight or polycarbonate lenses, identified with a note;

g) additional road lights following level crossing site survey;

h) adjustments necessary, e.g. to control tables, following survey of critical clearance points; and

i) TCAID devices found to be necessary following a search for leaf fall areas.


The scheme plan as a whole should then be reviewed to ensure that neither headways nor other signalling considerations have been compromised.

1.2 Signalling Plan A signalling plan is a scale layout plan, used to record, in a form that is readily understood by signal engineering and operations personnel, the current signalling facilities and identities. It is usually a derivative of the scheme plan, updated to all signalling alterations and amendments.

The signalling plan should fulfil the following purposes, as necessary:

a) general reference of all signalling functions;

b) deriving signal box and ground frame diagrams, panel faceplates, VDU map layouts and fixed diagrams, for the use of signallers (see Section 5.1);

c) providing additional information for signallers (where so determined by the infrastructure controller);

d) informing other operations personnel;

e) providing a plan that is acceptable to outside parties, joint enquiries, etc.

f) enabling control tables to be read (control tables should not be issued without a signalling plan);

g) facilitating preventative and corrective maintenance;

h) routine and incident testing;

i) providing a derivative for a location area plan (see Section 4.1); and



1 1 4 R A I L T R A C K


j) generating a new scheme plan for a proposed signalling alteration (see Section 1.1).

Separate signalling plans should be provided for every signal box or interlocking, showing all signalling functions controlled, supervised or monitored from the signal box. Where applicable, the plan should be extended to include the data collection area.

In addition to the items shown on the scheme plan, certain items from the location area plan (see Section 4.1) should also be shown, such as interlocking boundaries and track section information. See Section 5.1.1 for information to be supplied to the signaller.

Sufficient dimensioning should be provided in order to relate each sheet of the signalling plan to any adjacent sheet, or adjacent signalling plan, including signal to signal distances, where applicable. The name of each adjacent signal box should be stated, together with its prefix where relevant, at each extremity of the plan.

(Signalling plans were regionally known as domestic diagrams, locking sketches and numbering plans.)

1.3 SignaI Box Notes and General Notes These are a list of the key features of a signal box, or signalling scheme, including any functions that are not clear from the signalling / scheme plan.

These notes are not intended to replace operations instructions for the use of signallers (see GO/OT0018) and sufficient information should be separately supplied to the infrastructure controller to enable the signal box instructions to be compiled.

The term signal box notes also includes notes provided for:

• ground frames (including switch panels); • gate boxes; and • automatic level crossings.

They generally apply to the installation as a whole, rather than to individual interlockings.


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1.3.1 Format Signal box notes should be provided in one of the following forms:

• in full on the last sheet of the signalling / scheme plan; • adjacent to the symbol on the plan (e.g. for ground frames without a diagram,

or automatic level crossings without a separate plan); • in extract form adjacent to the symbol on the plan (for alterations to an

existing installation shown on a scheme plan); • as a separate (preferably A4) document, possibly generated from a computer

file (of an agreed format); or • on the signal box diagram (not for new work), or ground frame diagram, as

applicable.

1.3.2 Content The following information should be included in the general notes for the signalling system or installation as a whole:

a) constraints imposed on train operations, e.g. permitted and non-permitted types of train (see the route acceptance process described in GO/RT3270);

b) permissible speeds;

c) signalling design speed (where different from the permissible speed and documented in the design specification);

d) signal spacing curves used (see GK/RT0034),

e) maximum acceleration / deceleration data of traction units that have route acceptance, where required for determination of maximum attainable speed, e.g. in automatic level crossing regulation (see Part X of GK/RC0706);

f) design headways (non-stop and following stopping);

g) whether new signal positions and profiles have been amended to sighting committee recommendations, or "subject to signal sighting";

h) whether clearance points shown on the plan have been checked on site, or "subject to site survey";

i) type of electrification;

j) units of measurement (unless individually identified on the plan):

k) longitudinal scale (unless individually identified on the plan);

l) the version of signalling principles and design standards used (see Figure C1) in accordance with GK/RT0201;

m) source information (signalling plan version and site survey date), or "subject to site survey";

n) datum point used (with route if more than one); and

o) other essential signalling information for approval in principle that is not evident from the plan.

1.3.3 Typical Mechanical Signal Box The following information is typically required for a small mechanical signal box, unless it appears in some other form on the signalling plan, table of signal routes, or numbering grid:

a) whether elevated, platform, or ground mounted frame;

b) total number of levers;



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c) identities of spare levers, spaces, fixed levers (normal or reverse) and levers worked for interlocking purposes;

d) identity of any other function not shown on the plan;

e) whether illuminated diagram provided (or if more than one);

f) statement if non-block post;

g) type of block on each line and whether Welwyn control provided;

h) if track circuit block, type of emergency communication to adjacent block posts and method of describing trains;

i) if block post, whether block closing switch provided;

j) statement if absent switch provided (for level crossing purposes);

k) list of arms, slots and lamps repeated (semaphore only) with any groupings or special conditions;

l) list of track sections indicated;

m) list of electrically lit semaphore signals;

n) list of signals working automatically when lever reversed;

o) list of automatic signals with signaller's replacement devices;

p) list of any replacement indications that do not prove signals alight;

q) list of automatic signals with signal post replacement switches;

r) list of mechanically detected points (and if detected in one position only);

s) list of electrically detected points (unless power operated);

t) method of power operating points, where applicable, or list of points operated by each method;

u) if power operated, location of point handle and / or crank handle for the use of operating personnel in emergency;

v) whether FPLs stand normally out or in (usually out);

w) list of points with switch heaters provided and whether switching is automatic or timed;

x) list of electrically lit gate lamps provided, where applicable;

y) list of any controlled power operated barriers and state whether CCTV supervision and / or emergency local control is provided;

z) list of any automatic barriers monitored;

aa) list of any movable bridges indicated;

bb) conditions incorporated into train approaching indications, where applicable;

cc) list of signals with telephones;

dd) list of points with telephones;

ee) units of measurement and datum point (usually taken from the centre of the signal box); and


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ff) other essential signalling information that is not evident from the plan.

1.3.4 Typical Power Signal Box The following information is typically required for a large electrical or electronic signal box, unless it appears in some other form on the signalling plan or table of signal routes:

a) type of signalling control and display system provided (including number of electronic workstations, where applicable);

b) type of block on each line, type of emergency communication to next signal boxes and whether train describers provided;

c) type of remote control provided for each interlocking area and whether failure alarm and / or override / aIl-signals-on facility;

d) list of through routes set to work automatically when override initiated, where applicable;

e) list of junctions with selective override facilities;

f) list of stations with automatic platform working;

g) whether train operated route release is provided, or list of interlockings so equipped;

h) whether automatic route setting is provided, or list of interlockings so equipped;

i) list of interlockings with maintainer's monitoring panels;

j) statement if replacement devices are provided for all automatic signals not ordinarily operated from the signal box, or list those so equipped;

k) statement if all replacement indications prove signals alight, or list those that do not;

l) list any automatic signals with signal post replacement switches;

m) list of signals grouped for filament failure indication (or filament failure and power failure indication);

n) statement if telephones are provided at all colour light stop signals with the appropriate prefix (two illuminated telephones for tunnel signals, where applicable) and at all ground frames;

o) method of power operating points, where applicable, or list of points operated by each method;

p) list any mechanically operated points, e.g. at ground frames;

q) list any points provided with split detection and show ends grouped for indication purposes;

r) list any self restoring points and whether a failure alarm is given;

s) list any points requiring manual restoration (with alarm given);

t) location of point handle and / or crank handle for the use of operating personnel in emergency;

u) statement if all worked points are provided with switch heaters, or list those so equipped, identified to switching areas, and whether switching is automatic or timed;



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v) list any controlled power operated barriers and state whether CCTV supervision and / or emergency local control is provided;

w) list any automatic barriers monitored;

x) list any movable bridges indicated;

y) list any lockout devices provided;

z) list any incident detectors and state the emergency controls so imposed;

aa) conditions incorporated into train approaching indications, where applicable;

bb) statement if all relay rooms are fitted with intruder alarms;

cc) units of measurement and datum point (usually taken from the centre of each interlocking); and

dd) other essential signalling information that is not evident from the plan.

1.3.5 Typical Ground Frame The following information is typically required on the ground frame diagram (or on the signalling plan if the ground frame does not require a diagram):

a) whether elevated, platform, or ground mounted frame;

b) whether lever frame or switch panel;

c) whether shut inside facilities provided;

d) whether diagram provided (statement if illuminated);

e) list of track sections indicated (only with non-illuminated diagram);

f) list of mechanically detected points (and if detected in one position only);

g) list of electrically detected points (unless power operated);

h) method of power operating points, where applicable;

i) whether FPLs stand normally in or out (usually in);

j) list of points with switch heaters provided;

k) distance from the ground frame to the releasing signal box; and

l) units of measurement and datum point (usually taken from the centre of the ground frame).


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1.3.6 Typical Automatic Level Crossing The following information is typically required on the automatic level crossing signalling plan:

a) type of level crossing control e.g. AHBC, AOCL, MSL, etc;

b) protection provided, e.g. power operated half barriers;

c) whether trains are required to stop;

d) whether cattle-cum-trespass grids are provided;

e) any non-standard operation of audible warning devices and whether a tone change is provided for another train coming;

f) statement if the audible warning output is reduced between certain hours;

g) crossing road length;

h) minimum warning period in seconds;

i) statement if local control unit is provided;

j) monitoring signal box in which barriers are indicated (for AHBC) or in which the crossing equipment failure is indicated (for MSL) and to which the telephone(s) are connected;

k) distance from the monitoring signal box to the level crossing, or the crossing mileage (for unsupervised crossings);

l) permissible speed;

m) braking parameters used for crossing speed boards, where applicable;

n) maximum acceleration data of traction units that have route acceptance, where required for determination of maximum attainable crossing speed, e.g. where a station intervenes;

o) rail sighting distances to the crossing (for AOCL or ABCL);

p) failed alarm time; and

q) units of measurement and datum point(s).

1.4 Numbering Grids These are one or two dimensional grids listing all numbers or letters that have been used to identity signals, points, releases and track sections at a signal box.

Numbering grids are used to assist in numbering and lettering signalling functions on the scheme plan and provide the sequencing rationale required by GK/RT0009. They should be kept up to date to ensure any subsequent alterations do not result in the duplication of numbers or letters.

The grid may take various forms, such as:

a) a two dimensional grid (preferably on the signalling / scheme plan for the interlocking) listing the first digit in vertical columns and the second digit in horizontal rows;

b) a one dimensional grid along the bottom of a signalling plan; or c) a separate (preferably A4) sheet, possibly generated from a computer

database or spreadsheet (of an agreed format).

For signal boxes with more than one interlocking, the interlocking identity may be included on the grid.



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For lever frames, spare levers, spaces and fixed levers should be identified, unless this information is provided elsewhere.

1.5 Signal Spacing Parameters These are a tabular representation of the parameters that influence the relative positioning of signals, which satisfy the requirements of GK/RT0034 to keep certain signal spacing records.

Signal spacing parameters may be used to determine optimum signal positions on the scheme plan. They may also be used as a reference document when sighting signals initially, but should be kept up to date to ensure any subsequent alterations maintain signal spacing, headway and other requirements.

Any unusual features, such as deficient headway, use of a permanent speed restriction to obtain signal spacing, excessive over-spacing, or sites with combinations of steeply rising and falling gradients should be recorded and agreed by the infrastructure controller.

(Signal spacing parameter sheets were regionally known as signalling statistics, service braking tables, braking distance charts and signal braking calculations.)

1.5.1 Format They may take various forms, such as:

• a single (preferably A4) sheet for each signal; • a table for a number of signals; • a portion of line (up or down) on each sheet with aspect sequences shown; • combined with the signalling / scheme plan, aspect sequence chart, or

signal sighting notes; or • a printout from a computer database or spreadsheet (of an agreed format).

1.5.2 Content

a) The following data should be recorded for each signal:

i) post to post distances;

ii) total distance between first caution and signal at red;

iii) average gradient over the above distance, and gradient used to determine signal spacing in cases where GK/RT0034 requires an additional allowance to be provided;

iv) maximum speed for which spacing is available;

v) percentage over-spaced at permissible speed;

vi) information of the derived speed at the first caution (where permissible speed is not used);

vii) overlap at signal; and

viii) headway for following stopping and non-stop trains at each signal (if relevant).

The opportunity should be taken to check that the gradient information shown on the scheme plan is correctly plotted from the source used and is up to date, particularly where features or alignments have changed.

(b) The following information is required for the line:

i) signal spacing curve used (from GK/RT0034);


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ii) permissible speeds obtained from the sectional appendix, at the time of signal spacing (these may only be changed in accordance with GK/RT0007);

iii) headway requirement for each section of line (where specified); and

iv) maximum acceleration / deceleration data of traction units that have route acceptance, where required for determination of maximum attainable speed, e.g. in automatic level crossing regulation (at the time of signal spacing).

This information should be given in the general notes if the signal spacing parameters are combined with the signalling / scheme plan.

1.6 Aspect Sequence Charts These are charts showing the sequence of signal aspects for each state of the signalling system.

A diagrammatic representation of the aspects which may be displayed by each signal, aligned with the corresponding aspects displayed by consecutive signals.

Aspect sequence charts are used to ensure that all aspect sequences are in accordance with GK/RT0032. They may be used to compile control tables and should be kept up to date to ensure any subsequent alterations maintain correct aspect sequences. They are required for aspect sequence testing and are generally issued with the signalling / scheme plan.

The chart may take various forms, such as:

a) a portion of line (up or down) on each sheet with aspect sequences shown; b) combined with the signalling / scheme plan and/'or signal spacing parameters;

or c) a printout from a computer spreadsheet (of an agreed format).

The content should follow the example given in GK/RT0004. Any notes used should be explained on the chart.

1.7 Table of Signal Routes This is a comprehensive list of signal routes usually within the scheme plan design file.

Tables of signal routes are used to ensure that all routes required by the infrastructure controller have been provided and to enable any unusual features to be agreed. They may be used to compile control tables and to provide in formation to accompany the operating notice diagram. They are generally issued with the signalling / scheme plan.

1.7.1 Format The tables may take various forms, such as:

a) on the signalling / scheme plan with tables of routes adjacent to each signal; b) on the signalling / scheme plan with a route table on the end; or c) as a separate (preferably A4) document, possibly generated from a computer

file (of an agreed format).

The table should use the typical format given in GK/RT0004.

1.7.2 Special Notes Special notes may additionally include:

a) automatic working facility; b) replacement facility; c) controlled by gate box, but with telephone to supervising signal box; d) last wheel replacement facility;



1 2 2 R A I L T R A C K


e) alternative routes, via points reverse, etc; f) alternative overlaps; and g) override routes with a selective or through route facility.

Other special controls, such as those listed in Part F, may be shown for approval purposes.

Items (a) to (d), above, may alternatively be denoted by the appropriate symbol on the signalling / scheme plan.

1.8 Stage Scheme Plans Where the introduction of new or altered signalling is divided into sequential commissionings, derivative stage plans are required for each commissioning.

In order to divide a scheme into stages, a stagework strategy should be developed by liaison with other interested parties. This is initiated in the OPS and is progressed through the design specification (see Part C) and testing strategy. The responsibility for co-ordinating the design of signalling stagework with the other parties lies with the responsible design engineer. Once the new signalling functions which are to be commissioned at each stage have been agreed, stage plans may be produced.

The stage scheme plan for each stage is then a copy of the formally approved scheme plan showing the functions to be altered at that commissioning in red and green and omitting the functions for future commissioning.

Stage scheme plans should be submitted for approval where stageworks are to be approved in accordance with GK/RT0201.

Stage scheme plans should fulfil the following purposes, as necessary:

a) compiling stagework control tables, and other design details (note that each staged commissioning should be treated as a separate alteration with a separate set of drawings, irrespective of the timescale between stages);

b) providing derivatives for the production of stagework location area plans; c) creating the simplified plans required for operating notice diagrams and safety

diagrams (see Section 5); d) creating temporary alterations or patches to signal box diagrams or panels; e) functional and control table testing; and f) producing a temporary signalling plan for record purposes.

1.9 Signal Sighting Forms A sighting form depicts the profile and location of each signal together with the associated telephone, AWS inductor and any special requirements, as agreed by the signal sighting committee.

Signal sighting forms should fulfil the following purposes, as necessary:

a) recommending amendments to the scheme plan; b) recommending signal profiles used in the mechanical design of structures

(see Section 4.10); c) providing the sighting distances required to determine any approach release

requirements, for signals and associated route indicators; d) recording mileages of signals which are used in connection with the

calculation and publication of temporary speed restrictions (TSRs) - they allow signalling designers to inform permanent way engineers of the required location for TSR warning boards;

e) recording national grid map references of signals to enable the infrastructure controller to compile emergency services lists for issue to signal boxes and control; and

f) other purposes as described in GK/RT0037


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Each form should be signed by each representative member of the sighting committee and a copy issued to the record custodian and to the design authority. Each form should be numbered, dated, and version controlled in a similar manner to the scheme plan. For final records, however alteration letters may be used.

A typical form and an outline of the information required is given in GK/RT0037.

2 Level Crossing Ground Plans

This is a scaled and dimensioned drawing showing the position of all equipment, utilities and associated features in the vicinity of the level crossing, and the detail necessary for engineering, operating, maintenance and statutory requirements.

The plan, in different forms, is widely distributed to other functions and local authorities (including highways authorities) for proposal and subsequent construction purposes. (This includes the property discipline, where land purchase is involved.) The plan should be used to check the necessary interdisciplinary details and should also be sent to HMRI in support of the level crossing order, where required. Railtrack should have procedures in place to control the interfaces between disciplines. A public consultation meeting (for public level crossings) and, generally, a technical site meeting should be held.

Ground plans should be drawn to a scale that is not smaller than 1:100 for consultation, construction and record purposes, with sufficient detail to satisfy the HMRI Railway Safety Principles and Guidance (RSPG). The preferred size is AO, A1 or A2 although smaller versions may be used for specific purposes, such as site inspection, or to highlight particular information to different parties.

Typical symbols are given in Figure N3. (It is the intention that these symbols should be transferred to GK/RT0004 when next reviewed.) Guidance on level crossing design is given in GK/RC0706, Part X.

Each plan should be version controlled in a similar manner to the scheme plan. For final records, however, alteration letters may be used.

The record plan should incorporate the results of a site correlation.



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Figure N3 Typical Symbols for Level Crossing Ground Plans continued ...

Buildings (balconies on signal

Typical REB on Base (mirror

Barrier Base and Pedestal Boom < 6.6m,Right Hand, Left Hand

Typical Barrier Boom (3.6m shown)

Barrier Boom Light

Assembled Unit (right hand)

Assembled Unit (left hand)

Typical Barrier Base and Pedestal, Boom > 7.1m

Typical Barrier Boom (7.1m shown)

Barrier Side Arm

Assembled Unit (right hand)

Assembled Unit (left hand)

Cattle-cum-Trespass Guards

Insulated Rail Joint

Standard North Sign

Hedging

Trees

Grassed Areas

Land Level

Road Centreline Stud

Underground Electricity

UndergroundTelecommunications

Underground Gas

Underground Water

Overhead Electricity

OverheadTelecommunications (e.g.

British Telecomm)

Return Conductor

Signalling andTelecommunications

Buried Pipes or Ducts

Troughing Route

Telecom Stump Box

Turning Chamber/Manhole

.

N

EE

TT

GG

WW

OHL(E)

OHL(E)

S&TS&T

OHL(BT)

OHL(BT)

OHL(RC)

OHL(RC)

boxes to be shown)

Typical REB on Base(standard image)

image)

Typical REB on Base withWalkway (mirror image)

Apparatus Case

Emergency Hut

W.C. Cubicle

Weldmesh Fencing

Boundary Fence

Post and Rail Fence

Guard Rail

Pedestrian Gate(right hand shown)

Walls

CABLEENTRY

CABLEENTRY


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Figure N3 Typical Symbols for Level Crossing Ground Plans

Crossing IlluminationLight and Post

Miniature Stop Light Unit

Another Train Coming Unit

Flashing Red Pedestrian Light

Driver’s Crossing Light Units,New Style, Original Style

Driver’s Plunger Unit

Assembled Driver’s CrossingLight and Plunger Unit,

with Crossing Illumination

Local Control Unit, with Telephone

Public Telephone, Duplicate

Camera, Angle of View

Foundation and Baseplate forFlashing Road Signal

Standard Flashing Road SignalPost and Bracket

Standard Flashing Road Lights

Road Lights with Narrow Head

Standard Extension Arm

Yodalarm

Example of Complete Assemblywithout Extension Arm

Drop Light Column, 2 Head

Drop Light Column, 3 Head

Winch Light Column, 2 Head

Winch Light Column, 3 Head

Camera and Foundation,Outlet Left, Outlet Right

Flashing Road Lights, Elevation

Flashing Road Lights, Profile

Flashing Road Elevation of Assembled Lights Post Unit (3.2m post)

Barrier Pedestal Elevation (left hand shown)

Barrier Boom Light Elevation

Barrier Boom Elevation

Barrier Boom with Skirts

Assembled Unit with Skirts

SYMBOLS FOR ELEVATION DRAWING

3000mm



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2.1 Content The minimum detail to be shown on the ground plan is as follows:

a) Existing features from survey, or existing plan (after correlation):

i) the level crossing protection equipment (including relevant items shown in Figure N3), signals, telephones and point machines, and generally extending at least 30m along each rail approach;

ii) road alignment, markings (including the outline of yellow boxes), sign posts and sufficient highway dimensions to allow accurate marking, and generally extending at least 50m along each highway approach;

iii) tactile thresholds, kerbing and footways;

iv) decking, cattle-cum-trespass guards, guard rails, fencing, gates, access points and safe cess walkways;

v) underground and overhead utilities, where their position can be established from the relevant authorities (see GM/RT1103);

vi) electric traction equipment, including masts and overhead lines, where applicable; and

vii) adjacent property boundaries (whether public or private) and associated access (including structures or vegetation that could affect the view of the crossing by road or rail users).

b) New and altered under-track and under-road ducting and associated turning chambers, lineside location cases and earth works, and sufficient dimensioning to establish their positioning.

c) Layout details of the road works.

d) Construction details for the level crossing and other lineside equipment

e) All detail required for successful commissioning of the level crossing, dimensioned in relation to at least one datum point that is identifiable before and after construction.

f) Notes for the following purposes:

i) to uniquely specify level crossing equipment; ii) to identify specific actions and responsibilities of other functions,

disciplines or parties (not retained for record purposes); and iii) general notes, e.g. “All rail dimensions are to the running edge” and, for

reduced size plans, “Do not take scaled measurements from this drawing”; and

iv) any non-compliances to the RSPG.

Dimensioning should generally be shown in blue.

Due note should be taken of the effects of the siting of REBs and / or emergency manning facilities, crossing illumination and CCTV cameras upon adjacent properties to minimise the environmental impact.

2.2 Associated Information The following additional information should be provided, either on separate sheets, or inset on the ground plan:

a) An elevation view of the level crossing protection for each highway approach.


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b) Road signing arrangements for vehicular crossings: a scale or schematic plan showing road intersections, approach road signing and aiming points for the road traffic light arrays (unless tungsten halogen lamps with a wide angle spread). A scale plan should be provided where road curvature affects visibility.

c) For vehicular crossings, an illustrative vertical profile of the road through the crossing and its immediate approaches, on the nominal centre-line.

3 Control Tables A control table is a formal tabulation of the signal point and other controls associated with a signalling system, showing the interlocking and other dependencies between those controls. See Part M, Section 4 for control table convention.

Control tables should always be read in conjunction with the scheme plan, or signalling plan (for record purposes). Their production should use the information depicted on the plan, together with the associated table of signal routes and aspect sequence chart. Other requirements may be obtained from the OPS and associated documentation.

An amendment to the scheme plan may therefore necessitate amendments to the control tables.

Control tables should fulfil the following purposes, as necessary:

a) submitting for HMRI statutory approval as described in GK/RT0201; b) deriving information for signallers, such as signaller's route cards / list (see

GK/RT0026); c) producing engineering details, such as circuit diagrams and data; d) functional and control table testing; e) routine and incident testing; and f) updated for record purposes.

Safety is dependent on the capability of control tables being read and accurately interpreted by signal engineers with no previous knowledge of the particular signalling system concerned.

3.1 Control TabIes for Route Setting Interlockings The format of control tables for route setting systems should generally be in accordance with GK/RT0202, but see Part K for the current title block.

Some typical control tables (for the layout in Figure R12) are illustrated in Appendix F5 of GK/RC0706.

3.2 Control Tables for Non-Route Setting Interlockings Control tables for non-route setting systems should generally be based on the formats given in GK/RT0202, but with the route sheets adapted to suit signal interlocking and aspect controls.

3.3 Control Tables for Lever Frames In the case of lever frames, separate control tables should generally be provided for the mechanical locking (interlocking) and the electrical controls. Certain existing mechanical locking tables may be found on the signal box diagram, but this should not be perpetuated for new work.

The format of the electrical control tables should generally be in accordance with Table 5 of GK/RT0202. They should clearly distinguish between controls applied through the lever locks (i.e. at time of selection only) and those in the control circuits.

The mechanical locking tables should be arranged in a number of columns, as follows:



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a) lever No (either the first column, or middle column of three); b) RELEASED BY (where this column is omitted, its requirements should be

shown as lever reverse in the LOCKS column); c) LOCKS (may be subdivided into IN NORMAL POSITION and IN EITHER

POSITION); and d) optionally, RELEASES (the converse of RELEASED BY).

The RELEASED BY column implies lever reverse; otherwise lever reverse should be denoted as “8R" or as ". Conditions should thus be shown as

“(7 w 8R)" or as "(7w )”. A lever that is locked in either position (both normal

and reverse) should be denoted by “8B/W” (both ways) or by “(8, )”, unless a separate column is provided.

Where electrical interlocking is provided on mechanical lever frames, it is necessary to wire all the converses and counter conditional locking separately. In such cases, locking or transposition tables should be prepared that show the full requirements, in order to assist in the production of the electrical interlocking circuits.

Mechanical and electrical control tables for the typical layout are illustrated in Appendix F1 of GK/RC0706.

3.4 Track Section Schedule This is a tabulation of track circuits and axle counters for each interlocking.

For track circuits the cut-sections included in each track repeat relay (TPR) should be listed, together with their operating categories as defined in GK/RC0752, to enable appropriate time delays to be incorporated See Part M, Section 5.2 for the special TPR nomenclature. Common (centre) feeds should be identified and the relays of multi-relay track circuits should be separately quoted.

For axle counters, common heads used for counting in and counting out should be identified as well as any arrangement of multiple entrances or exits to a track section, together with the method of switching, where necessary.

Track section schedules should be provided, where documented in the design specification, to clearly interpret the track section requirements of control tables and assist in the design of engineering details and in testing. See Section 5.1.1 for information to be supplied to the signaller

4 Engineering Details This includes all design details required for construction or manufacturing purposes, including location area, bonding and cable plans, mechanical locking charts, circuit diagrams, data and details of the signalling control and display system.

Certain engineering details may form part of the product, e.g. illuminated diagrams and EPROMs (erasable programmable read only memory).

4.1 Location Area Plans This is a scale layout plan showing every signalling location, together with their identities, position and type of cases, interlocking boundaries, trackside functional module (TFM) identities, and the area of signalling equipment that is controlled by each location. The plan is usually a subversion of the signalling or scheme plan. Wherever practicable, it should be divided at interlocking boundaries, as described in Part M, Section 1.2.

The location area plan is built on the signalling / scheme plan by adding engineering details, not relevant to an operator but necessary for a designer to produce other design details.

The location area plan should fulfil the following purposes, as necessary:


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a) estimating and contract tendering (if available); b) designing location case circuit diagrams (including an extract of the location

area plan); c) designing bonding plans; d) laying out new equipment on site and identifying recoveries; e) updated for record purposes; and f) informing maintainers, to enable them to locate signalling functions on site.

Stage location area plans may be produced by using the stage scheme plans as the basis.

A location area plan for the typical layout is illustrated in Figure N4.



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Figure N4 Extract of Typical Location Area Plan (Derived from Figure N1)


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4.1.1 Content The following engineering details are required to be added to give sufficient information to allow circuits to be derived:

(In complex areas the plan may be clarified by using another colour to show the location areas and interlocking boundaries. The ancillary details which may be provided on the scheme plan, such as signal box notes, numbering grid, signal spacing parameters, aspect sequence chart and table of signal routes are not required on location area plans.)

a) Lineside locations (sited in accordance with GK/RC0821):

i) position, using the appropriate symbol; ii) identity (see GK/RT0009); iii) type (e.g. REB); iv) orientation, with a dot to represent a person looking into the front of the

case (this may be added after location siting); v) a broken lined box indicating the area controlled directly; and vi) the identity of certain equipment housed, (e.g. TFMs).

b) Interlockings:

i) position and name as shown on the signalling / scheme plan; ii) type (e.g. SSI, free-wired, Westpac IV, GEC geographical); iii) type of panel interface (e.g. processor; PBI ring, PIRU, ERSE); iv) type of remote control systems (e.g. SSI, TDM S2 FDM NV); v) type of train describer; vi) interlocking boundaries; and vii) any non-standard features.

c) Cable routes: the information listed in Section 4.4. Separate cable route plans may be provided, but they are generally combined with the location area plan.

d) Track sections:

i) boundaries and identities as shown on the signalling / scheme plan; ii) all additional cut-section boundaries, centre feeds and intermediate reed

Rx loops, using the appropriate symbols, the latter orientated towards the Tx;

iii) cut-section identities, in accordance with GK/RT0009 (if a Tx feeds more than one Rx, the combined identity, as used on the circuit diagram, e.g. AB1/2, should be quoted at a suitable point);

iv) type and / or frequency in brackets after the identity, as shown in GK/RT0004;

v) track feed/relay end connections, as identified in GK/RT0004; vi) low power TI 21 transmitters should be labelled “LP Tx”;

e) all impedance bonds, distinguishing between internal and external tuning:

i) track sections combined for indication purposes (with a note); and ii) cut-sections combined for monitoring purposes (with a note).

(Tuned zones need not be identified as such, but a note should identify any joints required in an otherwise jointless sequence.)

f) Other equipment:

i) equipment already shown on the signalling / scheme plan may be qualified by type where this would affect the controls or circuits, e.g. route indicators (FO = fibre optic; ML - multi-lamp; ST = stencil); and

ii) point machines (M3, 63, HW, etc.). Supplementary detectors should also be shown.

iii) Limits of contract, etc: these may be delineated, where appropriate, by the use of brackets.



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4.2 Bonding Plans This is a scale double line plan showing individual rails and position of insulated rail joints (IRJs), together with track circuit feed and relay connections with polarities, cross bonds, structure bonds and impedance bonds as applicable.

Bonding plans should be provided throughout electrified areas and elsewhere where track circuits exist. Wherever practicable, they should be divided at interlocking boundaries, as described in Part M, Section 1.2.

The bonding plan is the instrument of joint agreement between signal, electric traction and permanent way engineers, but see also Section 4.3 for S&C considerations. Railtrack should have procedures in place to control the interfaces between disciplines.

The bonding plan should fulfil the following purposes, as necessary:

a) checking interdisciplinary details associated with permanent way and electric traction requirements;

b) in electrified areas, informing the electric traction engineer of the requirements for yellow bonding, and seeking agreement over the position of impedance bonds for traction cross bonding purposes;

c) in a.c. and dual electrified areas, informing the electric traction engineer of the requirements for structure bonding;

d) in d.c. and dual electrified areas, informing the electric traction engineer of the requirements for conductor rail gaps, conductor rail protective boarding and areas of high current traction cable prohibition adjacent to AWS inductors;

e) laying out new bonding and tract circuit equipment on site and identifying recoveries;

f) checking bonding and equipment prior to commissioning;

g) informing the permanent way engineer of required IRJ positions;

h) identifying critical clearance and fouling points, and facilitating accurate site measurements;

i) designing location case circuit diagrams (including rail connection details);

j) facilitating preventative and corrective maintenance;

k) updated for record purposes; and

l) bonding correlation.

A bonding plan for the typical layout is illustrated in Figure N5.


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4.2.1 Content The following engineering details are required to be shown on bonding plans:

a) Structures and apparatus housings: only items that require to be earthed to the traction return system need be shown.

b) Train detection equipment: full details with all IRJs, track circuit bonding, rail connections and unique identifies, including track circuit interrupters, etc.

c) Any critical or sub-standard clearances at S&C should be identified and dimensioned to fouling point, with large scale (transverse and longitudinal) detail where necessary (see GK/RT0011). Note that any changes to the angle of crossing may require a recalculation of clearance distances.

d) Electrified areas: all traction bonding, including any red, yellow or structure bonding required; position of impedance bonds for cross bonding purposes; also continuity bonding of non track circuited lines.

e) D.C. and dual electrified areas: AWS inductors, with effective direction, and conductor rail gaps and protective boarding required.

f) Point operating mechanisms: if necessary to show detailed positioning (instead of on location area plan).

g) Scale or changes of scale.

h) Sufficient dimensioning to be able to relate the bonding plan to the associated scheme plan or location area plan

i) Reference to the next bonding plan at each extremity.



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Figure N5 Extract of Typical Bonding Plan (A.C. Electrified Area)


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4.2.2 Track Circuit Depiction The configuration of track circuits should be depicted in one of the following ways, as documented in the design specification:

a) both rails of double rail track circuits and the common rail of single rail track circuits shown by thin lines; and the insulated rail of single rail track circuits shown by a thick line; or

b) the insulated rail of single rail track circuits coloured throughout, together with any track circuit bonding connected to it; and both rails of double rail track circuits coloured (or the area between the rails possibly restricted to the first 25mm of the track circuit, provided that essential detail is not thereby obscured). Where jointless track circuits abut with a tuned zone, the nominal boundary should be shown by a diagonal line coloured appropriately on each side. The colours used should generally correspond with their depiction on the signalling display system, except where track circuits are grouped for indication purposes. (All cut-sections of a track circuit should be coloured as if they were one track circuit.)

Track circuit bonding should be depicted by thin lines. In electrified areas, traction bonding should be depicted by thick lines. Examples are given in GK/RT0252.

Guidance on track circuit design is given in GK/RC0706, Part T.

4.2.3 Track Circuit Bonding to be Shown All rail connections should be shown to assist bonding correlation. Each track circuit connection (or duplicated pair of connections) should be represented by a simple dot on the rail, identified using the feed / relay terminology of GK/RT0004. This applies to:

a) track circuit end (and centre) connections (for tail cables); b) track circuit rail to rail jumper connections (i.e. between separate sections of

non-traction rails); and c) any other connection to a non-traction rail, e.g. for TCAID equipment (see

GK/RC0762). (The rail connections to TCAIDs are to be permanently shown on bonding plans, even if the provision of the detector is seasonal.)

Fishplate type bonds are excluded, as they are provided to standard drawings. Impedance bond traction connections are covered by a separate symbol. Track circuit connections should be reproduced in greater detail on lineside location circuit diagrams (see Section 4.12.4).

4.2.4 Bonding Nomenclature Each track circuit bonding cable or rail connection should be uniquely identified on the bonding plan or circuit diagram by an alpha numeric code, with terms for the following elements, as applicable:

a) whether jumper cable (J) or tail cable (track circuit name); b) signal rail (S), common rail (C), or polarity (as GK/RT0004); c) feed / transmitter or relay / receiver end (as GK/RT0004); and d) duplication number (1 or 2), with 1 nearest to the IRJ.

4.2.5 Alternative Arrangements In d.c. electrified areas, separate plans may be produced to relieve congestion of the bonding plan, featuring:

a) track circuit bonding (known as a track plan); b) negative traction bonding; and c) conductor rail bonding, including traction isolation hook switches.

The term “bonding plan” used in this Code of Practice should include these plans, where applicable.



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4.2.6 Additional Information The following additional information is required:

a) date that the electric traction engineer requires the plan returned, incorporating the signalling requirements;

b) dates and limits of possessions; c) whether relaxations for non-conceptual work are to be used (see Part L); and d) details of any stagework planned.

4.3 Soleplate or S&C (Switch & Crossing) Plans This is a larger scale (often 1:100) permanent way plan provided in areas of S&C giving construction details of rails, switches, crossings, soleplates, timbers and bearers, etc, in accordance with GC/RT5011.

This plan is the instrument of joint agreement between permanent way and signalling engineers (and, in conductor rail areas, with the electric traction engineer). Railtrack should have procedures in place to control the interfaces between disciplines.

It should fulfil the following purposes, as necessary:

a) checking interdisciplinary details associated with permanent way and signalling requirements;

b) informing the permanent way engineer of required IRJ positions in areas of S&C;

c) informing the permanent way engineer of required fixing requirements for point fittings and track connections, including insulated soleplates and extended bearers;

d) identifying critical clearance and fouling points, and facilitating accurate site measurements (generally requires a minimum scale of 1:100); and

e) construction and other permanent way purposes, as necessary.

4.3.1 Content The following technical information is required:

a) location, e.g. nearest milepost; b) point end identification; c) method of point control and mechanisms to be fitted; d) type of bearer (concrete or timber); e) whether concrete drilling is permitted; f) extended bearers required and whether machines are left hand or right hand

drive; g) type of switches; h) type of rail, e.g. carbon or manganese; i) whether hardened rail is pre-drilled at manufacture; j) switch and stock rails to be pre-drilled for clamp lock mechanisms; k) type of any supplementary drive (mechanical or hydraulic); l) position of any supplementary drive (4 foot or 6 foot); m) number of supplementary detectors required, where applicable; n) any mounting plates or special drilling required; o) other equipment to be fitted, such as facing point locks or separate detectors; p) insulations required in soleplates and stretcher bars; q) position and type of rail connections, e.g. pin braze, pin drive, or cembre; r) whether duplicated connections are required; s) whether disconnection boxes are to be used; t) whether pre-formed cables are to be used; u) type of bonding (series or parallel) - see GK/RT0252; v) IRJs required; w) track circuit fouling and clearance points; x) stainless steel strip welded to rails; y) in d.c. traction areas, whether conductor rails are gapped for point

mechanisms; and z) a key to any symbols used that are not defined elsewhere.

Guidance on the design of point fittings is given in GK/RC0706, Part P.


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4.3.2 Additional Information The following additional information is required:

a) date that the permanent way engineer requires the plan returned, incorporating the signalling requirements;

b) dates and limits of possessions; c) whether relaxations for non-conceptual work are to be used (see Part L); and d) details of any stagework planned.

4.4 Cable Route Plan This is a layout plan showing the position of principal cable routes relative to the signal box, or interlocking, and lineside equipment location cases and REBs. This plan should generally be combined with the location area plan.

The following information derived from a cable route survey should be shown, in order to facilitate the construction of cable routes and under track crossings:

a) cable route position relative to lineside locations, signal posts, etc, including the minimum distance from the running edge;

b) type: [SCT] = surface concrete troughing [BCT] = buried concrete troughing [BD] = buried direct (non-preferred) [BKS] = on brackets [BTR] = buried tube route;

c) turning chambers, manholes or cable pits; d) under-track crossings, quoting the depth and the number of ducts; e) the depth of buried cables; f) the position of through joints in main multicore cables; and g) the dimensions of each item from a known datum.

GM/RT1103 specifies the records that must be kept of buried cables.

Guidance on cable route design is given in GK/RC0706, Part J.

4.5 Cable Schematic Plan This is a plan showing all signalling cables required, together with sizes, to be installed between signal boxes or interlockings and locations. It should be divided at interlocking boundaries, as described in Part M, Section 1.2.

It should fulfil the following purposes, as necessary:

a) cable ordering; b) planning and running of cable laying trains; c) producing other design details, such as cable core plans; d) updated for record purposes; and e) alterations to depict proposed signalling work.

A cable schematic plan for the typical layout is illustrated in Figure N6.

Guidance on cable design is given in GK/RC0706, Part J.



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Figure N6 Typical Cable Schematic Plan


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4.5.1 Content The following information is required for each main multicore cable, datalink cable and power cable. Tail cables are not to be shown.

a) cable size; b) number of conductors; c) specification and type of cable; d) unique cable name (see Part M, Section 6.2 for nomenclature); e) for power cables, whether copper (Cu) or aluminium (Al) conductors; f) locations in which the cables are terminated; g) the distance between locations; h) the position of any cable joints, dimensioned to the nearest location or other

feature; i) repeater (or cut-section) locations (where designated); and j) any requirement for diverse routes between locations to be used.

The distance between locations should be obtained from the location area plan and a note added, that for cable running purposes an additional allowance should be made for under track crossings and termination of cables.

Where locations are designated as repeater (or cut-section) locations for the purposes of immunisation or voltage drop due to the length of line circuits these may be identified by adding (C/S) after the location name.

4.6 Cable Core Plan This is a plan showing the allocation of signalling functions to specific cores in multicore and data link cables. It should be divided at interlocking boundaries, as described in Part M, Section 1.2.

Cable core plans are required to be used for:

a) commissioning testing; b) producing other design details, such as circuit diagram termination sheets and

power supply wiring; c) updated for record purposes; d) routine and incident testing; e) facilitating preventative and corrective maintenance; f) correlating actual site wiring to records; and g) alterations to depict proposed signalling work.

A typical cable core plan is illustrated in Figure N7.

Guidance on cable design is given in GK/RC0706, Part J.



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Figure N7 Typical Cable Core Plan


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4.6.1 Content The following information is required for each main multicore and datalink cable: (Power cables and tail cables should not be shown.)

a) cable size; b) number of conductors; c) specification and type of cable; d) unique cable name (see Part M, Section 6.2 for nomenclature); e) locations in which the cables are terminated; f) cable core numbers and allocations; g) which cores are connected through at each location; and h) repeater (or cut-section) locations (where designated).

The naming of cable cores should correspond to the circuit names on the respective cable termination sheets.

4.7 Power Distribution Plan This is a plan showing the power supply distribution arrangements to assist in compliance with Electricity at Work Regulations.

This plan is also the instrument of joint agreement between signalling and power supply engineers and should be used to check the necessary interdisciplinary details. Railtrack should have procedures in place to control the interfaces between disciplines.

A separate power distribution plan should be provided for each power source, and not be dived at interlocking boundaries, unless the boundaries are co-incident.

A power distribution plan for the typical layout is illustrated in Figure N8.

The following information is required on the power schematic plan, using symbols to BS 3939;

a) main supply point, with total loadings and ratings; b) standby supply arrangements; c) distribution circuits (single supply line only), with cable size; d) signal boxes, interlockings, location cases and REBs; e) supply transformers and transformer / rectifiers with ratings; f) busbars and overcurrent protective devices (generally fuses) with ratings, up

to and including the 110V location input fuses: g) all switching and isolation points; h) normally open switches or links to be identified with a note; i) relay room and feeder loadings and ratings; j) locations having an additional supply from another source to be clearly

identified; and k) 120V d.c. or 110V a.c. supply systems, including multicore distribution.

It is important that feeder loadings are kept updated as equipment is altered, to ensure that power supply arrangements remain dependable.

Guidance on power supply design is given in GK/RC0706, Part C.

4.8 Mechanical Locking Charts and Lever Details This is a chart showing the actual mechanical locking arrangements required to achieve the control tables of mechanical locking.

Mechanical locking charts for different types of mechanical locking are illustrated in Appendix F1 of GK/RC0706.



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Figure N8 Typical Power Distribution Plan


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The chart should be orientated with lever one on the left, whether the locking is behind or in front of the frame.

(Mechanical locking charts were also known as dog charts, locking diagrams or tappet diagrams.)

4.8.1 Content The following additional information should be shown or referenced on the mechanical locking chart (a cross section drawing may be provided):

a) pattern of lever frame, e.g. LM 1943, McK&H No.17, Stevens; b) method of operation, e.g. catch handle, direct action, duplex; c) type of locking, e.g. tappet, Midland tumbler, L&NW tumbler; d) pitch or centres of levers; e) number of levers; f) arrangement and position of locking boxes or trays; g) arrangement of channels within the locking box; h) length of tappets and stroke, in relation to width of channels; i) shortened levers; and j) position of spare levers and spaces.

4.8.2 Associated Information The following should also be provided, either on the mechanical locking chart, or separately:

a) schedule of lever nomenclature plates; b) lever painting details; and c) mechanical operation details (see Section 4.9).

Lever nomenclature plates, with painting details, are illustrated in Appendix F1 of GK/RC0706.

4.9 Mechanical Operation Details These are the details required to record the provision of mechanical equipment and enable a design to plan alterations.

The following details should be provided:

a) any special quadrants; b) position of lever locks, lock slides, economisers and Annetts locks, etc; c) position and size of circuit controllers and linkage (or on lever lock and circuit

controller analysis - see Section 4.11.10); d) position of standards and supports and method of fixing apparatus; e) levers with draught wheels, wire adjusters, or counterweights, and their

position; f) compensation arrangements for point rodding; g) slotting arrangements for signals; h) mechanical detection details; i) position of insulating joints in rodding and wires; j) results of any calculations; k) adjustments required on site; and l) special arrangements, restrictions, or precautions.

Guidance on mechanical interlocking design is given in GK/RC0706, Appendix F1, mechanical point design in GK/RC0706, Appendix P1, and mechanical signal design in GK/RC0706, Appendix S1.

4.10 Mechanical Engineering Details for Points and Signals Mechanical details should be provided for point layouts and signal structures. Where these follow a standard arrangement, the appropriate mechanical equipment drawings (including version) may be quoted on the circuit diagrams or on the reference sheet (see Section 4.11.2).



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Mechanical drawings should accord with BS 308 and bear a mechanical drawing grid to the left of the title block. An example is shown in Figure N9.

NotesAll dimensions in millimetresunless otherwise stated.General tolerance + -Do not scale. If in doubt ask.Drawn to BS 308. Spec. No.

Material Finish

Type Approved

Figure N9 Mechanical Drawing Grid

4.11 Signal Box and Interlocking Circuit Diagrams Signal box and interlocking circuit diagrams should comprise all applicable sheets, generally arranged as follows:

4.11.1 Index Sheet See Part K, Section 2.

4.11.2 Explanation or Reference Sheets These are supplementary sheets provided to explain unusual or significant features within the interlocking, particularly any that might create a hazard for the unwary.

The following information should typically be included:

a) the version of signalling principles and design standards used (see Figure C1), unless clearly stated on the signalling plan in accordance with GK/RT0201;

b) sheets showing the internal wiring or pre-wired units, unless it is shown in full on circuit diagrams (see Part M, Section 5.6);

c) special symbols, keys and defaults (see Part M, Section 6.1) used on the circuit diagrams;

d) reference to operational and maintenance manuals or specifications (which should be kept for the life of the installation), together with the identify of the relevant equipment (see Section 5);

e) explanations of unusual design features, particularly for applications with no established safety record;

f) reference to the signalling system and sub-systems approval status (see GK/RT0104), the means of safety assurance and the level of safety provided (see GK/RT0206);

g) reference to any equipment specification (see Part M, Section 7), standard drawings (see Section 4.10) or application criteria not stated elsewhere;

h) reference to any specific safety cases or risk assessment reports, with a statement of any special mitigation measures applied (see Part R);

i) known system safety hazards that have been addressed and those that have not been addressed (see Appendix B2 of GK/RC0706);

j) a note of any particular occupational safety hazard from signalling equipment that cannot be eliminated at source, to help personnel manage the risks (see Part Q); and


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k) other information to be made available for the life of the installation under the Construction (Design and Management) Regulations, unless the health and safety file gives adequate access (see GK/RT0201).

4.11.3 Equipment Room Layout This is a scale plan of the equipment room, showing the position of:

a) relay racks: b) electronic cubicles; c) power rack / cubicle; d) cable termination rack; e) cable trunking and ducting; f) monitoring equipment, where provided; g) plan table and drawing cabinets for keeping records; h) heating, lighting and air conditioning equipment; i) doors, emergency exits, fire extinguishers and other essential health and

safety information; j) regional electricity company incoming supply, main earthing terminal,

telephone and power socket outlets; and k) any other necessary details.

Guidance on apparatus housing design is given in GK/RC0706, Part G.

4.11.4 Equipment Rack Layout A front view of the rack or electronic cubicle should be shown, with profiles of all equipment, fuses and terminals drawn proportionally, allowing space for equipment rails and ducting. In the case of apparatus cases annexed to an equipment room, front and rear views should be shown.

Equipment name and type, or relay name, pin code and contact configuration (e.g. 12F4B) should be stated to assist profile correlation and a reference should be given to the sheets on which the analysis can be found.

The type of all equipment should be quoted on the rack layout, together with any other details necessary to uniquely specify each item required, as given in Part M, Section 7. Where class II (double insulated) equipment is required, this should also be stated.

The size of rack mounted equipment should be specified. Design details should cater for the maximum size of equipment as stipulated in current specifications.

Where terminals are required to be fully shrouded to protect them from items being dropped, or to protect personnel from dangerous voltages, a suitable note should be added. (See GK/RC0706, Part D.)

Where special restrictions apply to positioning or wiring of equipment, this should be clearly shown on circuit diagrams or rack / case layouts, so that if alterations are made at a later date the restrictions are readily apparent.

Whenever non-suppressed reed, axle counting, or SSI equipment is mounted, a warning notice should be shown to be affixed to equipment racks and apparatus cases (inside the door), prohibiting the use of portable radio transmitters, mobile telephones, vacuum cleaners or power tools within one metre.

For REBs, construction details may be required, showing the position of the primary framework components and ducting. Unless otherwise specified, these should be based on the BRS-SM440 series drawings which give details of the standard signalling equipment framework. However, the construction drawings may take precedence over the standard arrangement.

4.11.5 Electronic System Schematic and Allocation Sub-system configuration with the necessary interconnections should be shown, in order to illustrate the system architecture, as described in GK/RT0206. A block diagram may be used.



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Transmission channels and input / output functions should be tabulated on analysis or allocation sheets, as described in Part M, Section 5.3. The wiring sheet number on which the interface circuit is shown should be quoted.

See the appropriate system applications manual for the full information required.

See the SSI applications manual for the means of generating trackside functional module (TFM) allocations and data link telegrams for issue to maintainers and testers. A typical TFM allocation is shown in Gk/RC0706, Appendix F4.

See Section 4.11.22 for external systems.

4.11.6 Inter-Rack / Cubicle Cable Schematic Analysis Where relay racks or cubicles are designed to be pre-wired and connected together with multicore cables, these cable terminations should be analysed to assist wire count correlation, showing the sheet where used, and the number of wires on the internal side. The unique name, size and destination of all cables should also be shown. A schematic plan showing all such inter-rack cables may also be provided. Cable core plans are not required.

4.11.7 Power Cubicle / Rack Layout This is a proportional drawing showing the position of all power equipment, fuses and links situated in the power cubicle or on the power rack.

4.11.8 Power Supply and Earthing Arrangements These drawings should show:

a) the power supply point at which each incoming power feeder originates and the next disconnection point of all feeders;

b) switching & isolation points, busbars and overcurrent protective devices (generally fuses) with ratings;

c) main and standby power supply circuits, including uninterruptible power supplies (upss) and charging arrangements;

d) automatic changeover circuits; e) normally open switches or links to be identified with a note; f) transformers and transformer rectifiers with ratings; g) volt meters and ammeters; h) earth fault, under voltage and power off detection circuits and monitoring, as

required; i) earth bonding and protective conductors; j) the minimum earth impedance required, either earth fault loop impedance or

earth electrode resistance; and k) warning notices to be displayed and equipment or terminals that should be

shrouded to protect personnel from dangerous voltages. (See GK/RC0706, Part D.)

Where it is necessary to use reduced sensitivity or slow operation overcurrent protection devices to avoid nuisance tripping from motor starting currents or transformer inrush currents, etc, an appropriate note should be made on the design details.

Where class II electrical systems are used, a warning note should be provided on the design details to prevent the connection of any equipment other than class II.

Guidance on power supply design is given in GK/RC0706, Part C.

4.11.9 Fuse Analysis Power supply fuses and terminals should be analysed to assist wire count correlation, showing the sheet where used, and the number of wires on each terminal. Fuse ratings and circuit names, or descriptions, should also be shown.


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4.11.10 Lever Lock and Circuit Controller Analysis Lever locks and bands should be analysed to assist wire count correlation, showing the sheet where used, and the number of wires on each terminal. The cut of the lock, provision of lock proving contacts, number of bands available and position of each band should be shown. The type of lock and controller, and force down feature where provided, should also be stated.

Guidance on the design of locks and controllers is given in GK/RC0706, Appendix F1.

4.11.11 Contact Analysis The style of relay analysis should be chosen to facilitate accurate design, correlation, construction and maintenance.

The following should be analysed to assist wire count correlation, showing the number of wires on each terminal and the sheet where used. Relay types, pin codes and contact configurations should also be shown.

a) Relay contacts and coils. Relay analysis should generally be in rack layout order, rather than alphabetical or type order, in order to facilitate future alterations. One of the following styles may be adopted:

i) a matrix with contact identities across the top and relay names down the side (more compact, but less easy to view, particularly on a computer screen) - see example in Future N10; or

ii) footprint style showing the rear view of each relay separately (with perhaps 15 on the sheet, equivalent to one row of an apparatus case) - see example in Figure N17.

b) Other plug-in units, such as converters;

c) Multi-way plug couplers (see Section 4.11.5 for electronic systems);

d) Other equipment shown on more than one wiring sheet.

See Part M, Section 8 for analysis convention.

4.11.12 Cable Termination Rack Layout This is a proportional drawing showing the position of all cable terminations. The identity of each vertical column and the number of terminals in each should be shown. See Part M, Section 6.4 for nomenclature.

Guidance on the design of cable terminations is given in GK/RC0706, Part J.



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Figure N10 Typical Relay Contact Analysis (Matrix Style)


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4.11.13 Cable Termination Analysis Cable terminations should be analysed to assist wire count correlation, showing the sheet where used, the circuit name and the number of wires on the internal side. The unique name, size and destination of all cables should also be shown.

Where terminals are required to be fully shrouded to protect them from items being dropped, or to protect personnel from dangerous voltages, a suitable note should be added. (See GK/RC0706, Part D.)

Where FDM systems are in use, a “through crimped” note should be added.

In existing installations where separate sliding links are not provided for every incoming and outgoing cable, a note should be inscribed on all cable termination sheets: “All Single Post Terminations to be Fitted with Red Dome Nuts”, to act as a reminder in case cable fault jumpering becomes necessary.

An example of a cable termination analysis sheet is illustrated in Figure N16.

4.11.14 Temporary Approach Control and Route Disconnection Link Analysis This is an analysis which immediately identifies where these links may be found in the equipment room. They should be mounted in two distinct groups on the terminal rack and clearly labelled.

4.11.15 Remote Control and Train Describer Interface Circuits This generally comprises the feeds to buffer relays or interface tag blocks.

4.11.16 Interlocking, Control and Associated Circuits Typical circuits for free-wired relay or electro-mechanical interlockings and level crossings may be used as a basis (see References), but require to be fully checked for the particular application.

The circuits should generally be arranged in numerical order within the following groups:

a) Main Signals: interlocking, selection and repeater circuits; b) Shunt Signals: interlocking, selection and repeater circuits; c) Points: interlocking, operation and detection circuits; d) Ground Frames: interlocking, release and proving circuits; e) Level Crossings: manual control and CCTV circuits; f) Track Circuits: repeater and route stick circuits; g) Miscellaneous Functions: as necessary.

See Part M, Section 5 for circuit diagram convention.

Guidance on circuit design is given in GK/RC0706, Part D, and on interlocking design in GK/RC0706, Part F.

4.11.17 Alarm and Indication Circuits The various signal box circuits may include those for:

a) emergency box to box alarms; b) combining the various functions which operate the common audible panel

alarms; c) train ready to start audible indications; d) remote control or electronic system failure alarms and visual displays; e) level crossing alarms, including automatic level crossing supervision; f) alarm acknowledgement push buttons; g) other special switching circuits, such as first filament failure and power

monitoring alarms; h) other audible annunciators.

4.11.18 Signalling Control and Display System Circuits These may include:



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a) the circuits feeding the signalling control and display system control devices and indications;

b) panel looping, generally on a reverse derivative of the panel faceplate drawing;

c) at an electro-mechanical signal box, the signaller’s illuminated diagram and block shelf wiring;

d) at SSI or remote interlockings, an all-signals-on circuit; e) where required for remote interlockings, a system of override control circuits

for use in the event of a failure of the main remote control system; f) replacement circuits for automatic signals.

Guidance on the design of control and display systems is given in GK/RC0706, Part L.

4.11.19 Fusing and Looping Arrangements This is the wiring of the supply and return feeds arranged in order of fuse or terminal. The wiring of test points should also be shown.

4.11.20 Maintainer’s Monitoring Panel Circuits These are the circuits feeding the interlocking monitoring indications, or any emergency panel.

4.11.21 Level Crossing Schematics These are provided where documented in the design specification, or where of benefit to the designer, for level crossings with complex controls or overlapping strike-ins, showing all external circuits in single line form, but without relay contact, fuse, or terminal allocations. They should be kept with either the signal box or location circuit diagrams, as appropriate (but not with both, lest the updating of one be neglected).

Guidance on level crossing design is given in GK/RC0706, Part X.

4.11.22 System Schematics (External) These should be provided for every remote control system (e.g. TDM, FDM and SSI), showing:

a) cabling details; b) the location of any line amplifiers or line isolating transformers; c) the location of office and field stations (for TDM); d) the location of all receivers and transmitters, with function names and

frequencies (for FDM); and e) details of data link cabling and connections to TFMs (for SSI).

Transmission channel allocations should be provided as described in Section 4.11.5.

See the appropriate system applications manual for the full information required. A typical TFM schematic is shown in Gk/RC0706, Appendix F4.

4.12 Lineside Location Circuit Diagrams With more than one apparatus case at a location, the details should be provided on a single set of drawings. Each such drawing should clearly identify the case in which each part of the depicted circuit, or equipment, is located, generally by the use of brackets at the top of the sheet.

All disconnection boxes should be shown on circuit diagrams.

Sheets from a set of location diagrams for the typical layout are given in Figures N11 to N17. See Part M, Section 5 for circuit diagram convention.

Lineside location circuit diagrams should comprise all applicable sheets, generally arranged as follows:


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4.12.1 Location Circuit Diagrams: Frontsheet It is necessary to provide an extract of the location area plan, showing the position on the ground of all trackside equipment controlled from the location. This extract may be provided on the index sheet for the location.

An index and frontsheet for a typical location is illustrated in Figure N11.

4.12.2 Location Circuit Diagrams: Case or Equipment Room Layout Construction details should be provided if required, showing the position of the primary framework components and ducting. Unless otherwise specified, these should be based on the BRS-SM440 series drawings which give details of the standard signalling equipment framework. However, the construction drawings may take precedence over the standard arrangement.

Front and rear apparatus case, or rack, views should be shown, with profiles of all equipment, fuses and terminals drawn proportionally, allowing space for equipment rails and ducting. In the case of equipment racks and electronic cubicles in an equipment room, a front view alone is generally sufficient.

The front of an apparatus case is the side on which the face of equipment is mounted and where relay operation or status indications may be observed.

Other details should be provided as described in Section 4.11.4.

For equipment rooms and buildings an equipment room layout should also be provided, as described in Section 4.11.3.

An apparatus case layout for the typical location is illustrated in Figure N12. Guidance on apparatus housing design is given in GK/RC0706, Part G.

4.12.3 Location Circuit Diagrams: Power Supplies and Busbar Analysis These drawings should show the details prescribed in Section 4.11.8. In addition the following information should be shown:

• local batteries with charging arrangements; • power supply fuse and terminal analysis, giving circuit names; and • power supply looping.

Where supplies are present from more than one power supply point, each should be clearly named.

A power supply for the typical location is illustrated in Figure N13. Guidance on power supply design is given in GK/RC0706, Part C.



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Figure N11 Typical Location Index and Frontsheet


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Figure N12 Typical Apparatus Case Layout



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Figure N13 Typical Location Power Supplies


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Figure N14 Typical Location Train Detection Circuits



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4.12.4 Location Circuit Diagrams: Train Detection Circuits These drawings should show:

a) outgoing track circuit repeater circuits; b) track circuit equipment wiring; c) rail connections, identifiably to the bonding plan (see Section 4.2), and tail

cables (with maximum lengths, where critical, e.g. high frequency track circuits). Duplicated tail cables should be separately shown, with reference to diverse routing, where applicable;

d) disconnection box and / or impedance bond internal wiring (with straps shown);

e) treadle or axle counter circuits.

Track circuit connections should be reproduced in detail, showing disconnection box or impedance bond terminals, rail connection points, IRJ positions, line name and up / down direction. Double rail track connections associated with impedance bonds should be termed (COIL) and (RAIL).

If necessary to avoid causing a nuisance to local residents, sound proofing of tuning units emitting an audible frequency should be specified on the design details.

Train detection circuits for the typical location are illustrated in Figure N14. Guidance on train detection design is given in GK/RC0706, Part T.

4.12.5 Location Circuit Diagrams: Signal Circuits These drawings should show:

a) incoming signal control circuits, showing the through circuit back to its origin, unless originating from an interlocking;

b) outgoing signal repeater circuits; c) signal lighting circuits and tail cables (with maximum lengths, where critical,

e.g. low voltage battery backed signals); d) signal head internal wiring (with straps shown); e) AWS (or other protection system) circuits; and f) first filament failure circuits.

Signal circuits for the typical location are illustrated in Figure N15. Guidance on signal design is given in GK/RC0706, Part S.

4.12.6 Location Circuit Diagrams: Point Circuits These drawings should show:

a) incoming point control circuits, showing the through circuit back to its origin, unless originating from an interlocking;

b) outgoing point detection circuits; c) point detection feed and trackside circuits and tail cables (separate cables for

outgoing and incoming detection); d) supplementary detector circuits, showing the orientation of the detector on an

extract of the layout (with an arrow indicating the cable entry); and e) point machine/clamp lock internal wiring (with straps shown).

Guidance on point design is given in GK/RC0706, Part P.

4.12.7 Location Circuit Diagrams: Miscellaneous Circuits These drawings should show:

a) apparatus case heater wiring (800Ω, 15W), with separate fuse; b) where documented in the design specification, apparatus case lighting,

switched, with separate fuse; c) where specified, maintenance telephone plug points; d) ground frame circuits; e) level crossing circuits; and f) other circuits as required.

Guidance on circuit design is given in GK/RC0706, Part D


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Figure N15 Typical Location Signal Circuits



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4.12.8 Location Circuit Diagrams: Analysis The following should be analysed to assist wire count correlation, showing the number of wires on each terminal (except for cables where only one wire is permitted):

• relay contacts and coils, as section 4;11;11; • other equipment shown on more than one wiring sheet; • cable terminations, showing circuit names, as section 4;11;13; and • electronic system input / output allocation, as Section 4.11.5.

For power supply fuses and terminals see Section 4.12.3.

Sheet numbers need not be quoted for small locations (say of less than 10 sheets).

Where FDM systems are in use, a “though crimped” note should be added. The unique name, size and destination of all cables should also be shown.

In existing installations where separate sliding links are not provided for every incoming and outgoing cable, the following note should be inscribed on all cable termination sheets: “All Single Post Terminations to be Fitted with Red Dome Nuts”, to act as a reminder in case cable fault jumpering becomes necessary.

Analysis sheets for the typical location are illustrated in Figures N16 and N17.

4.13 Electronic System Details The details required are dependent on the electronic system. The following details should be specified for a programmable system:

a) hardware (see Sections 4.11.5 and 4.11.22); and b) software (see Section 4.13.1).

The software / hardware interfaces must be compatible.

Guidance on electronic interlocking design is given in GK/RC0706, Appendix F4.

4.13.1 Data This is site specific geographical and control information in an electronic form, which may be of a safety-critical nature or otherwise. (Safety integrity levels are considered in GK/RT0206, Appendix B.)

The data may generally be divided into the following categories:

• system program or fixed data, in accordance with the appropriate system applications manual;

• geographical data, which configures the program to a particular site, is prepared on a workstation by the data designer and specified by means of data listings; and

• variable data, which records the real-time state of signalling functions.

In order to be used in an electronic system or sub-system, geographical data from master data files on the workstation is usually permanently stored in an EPROM.

Further details of data production processes are given in Part D. See the appropriate system applications manual for the data style to be used.

Configuration control should be maintained by means of status record index sheets, as described in Part K. (This should be applied to the system program and geographical data, both of which must be compatible.)


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Figure N16 Typical Location Cable Termination Analysis



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Figure N17 Typical Location Relay Analysis (Footprint Style)


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4.13.2 Map Search Plan A map search plan may be prepared from the signalling plan.

This utilises a simplified signalling plan to show the extent and access points of the map with separate drawings for the up and down directions of travel. The drawings are used when preparing map data and when using the map in other areas of data for approach lock releases and train operated release in electronic interlockings.

Where required a similar map search plan should be produced for train activated warning system purposes.

4.13.3 Sub-Route and Sub-overlap Plans Sub-route and sub-overlap plans may be prepared from the signalling plan.

These utilise a simplified signalling plan to show the extent and identity of each sub-route and sub-overlap required. The plans are used to assist with preparing the data associated with route locking and release in electronic interlockings.

A typical sub-route and sub-overlap plan is shown in GK/RC0706, Appendix F4. Similar route plans are required to specify automatic route setting (ARS) sub-areas.

4.13.4 Train Describer System Details The following additional details may be required:

a) block schematics; b) berth tables; c) data tables; d) keyboard layouts; e) TD maps; f) map schedules; g) stepping tables; and h) translation tables.

These details require interdisciplinary checking for signallers’, operating, train reporting and performance data collection requirements. Railtrack should have procedures in place to control the interfaces between disciplines.

Guidance on train describer design is given in GK/RC0706, Part M.

5 Operational and Maintenance Details

Sufficient operational and maintenance details should be provided to enable safe operation and maintenance of the signalling system and to facilitate whole life asset management in accordance with GK/RT0170.

Reference may be made to the maintenance specifications in GK/RH0750.

The requirements for operational and maintenance manuals for propriety equipment should be documented in the design specification. It is essential that such manuals are uniquely identified to the equipment concerned. (See Part K for the configuration control necessary.) They may be listed on the reference sheet at the front of the circuit diagrams, together with the relevant equipment identify (see Section 4.11.2).

The following information should also be provided:

5.1 Signalling Control and Display System Details These should be based on a layout plan showing the signalling features, controls and indications to be presented to the signaller in accordance with GK/RT0025.



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They are also used to check interdisciplinary details associated with signallers and operating requirements. Railtrack should have procedures in place to control the interfaces between disciplines.

The details presented to the signaller should be clear and concise, and should consider the ergonomics of operation.

The following details may be required, depending on the type of system(s):

a) full size visual display unit (VDU) may layouts, used in data preparation, for each screen overview or detailed view on a VDU;

b) a fixed diagram for VDU based systems, a copy of which is prepared for mounting in the signal box;

c) signalling panel faceplate, used for manufacturing purposes and a derivative of which is used to show wiring and looping details (see Section 4.11.18);

d) signal box diagram (usually associated with lever frame or individual function switch type installations), a copy of which is prepared for mounting above the signaller’s controls and may incorporate illuminated indications;

e) ground frame diagram (including switch panels), provided whether there is a risk of confusion to the ground frame operator (illuminated indications, such as free light and detection of power operated points, etc. may be provided separately) - see also GK/RT0061;

f) construction details and floor plans for signalling workstations, consoles, displays, block shelves, switch panels and lever frames; and

g) maintainer’s monitoring panels, or any emergency panel faceplate, used for manufacturing purposes and a derivative of which is used to show wiring and looping details (see Section 4.11.20).

Hardware details and data for panel processors, signaller’s display and other electronic systems are covered in Section 4.13. For wiring details and panel tag block analysis see Section 4.11.18.

Signal box diagrams, panel faceplates and VDU maps, when parallel to the track, should generally be mounted in their correct geographical orientation, as viewed by the signaller facing the display.

Guidance on the design of control and display systems is given in GK/RC0706, Part L.

5.1.1 Additional Information for Signallers Where a signalling plan is not supplied for the use of signallers, the following information should be separately provided in accordance with GK/RT0025, unless shown permanently on the signalling display:

a) the location of all level crossings (with and without telephones); b) the location of road bridges and access points; c) limits of systems for the protection of personnel (see Section 5.2); d) electric traction limits and isolation gaps (see Section 5.3) - note that signals

protecting isolation gaps on d.c. lines should be clearly identified on the signalling display (because of potential risks to detrained passengers);

e) signaller’s route lists (see Section 5.4); f) list of axle counter track sections (see Section 3.4); g) boundaries of interlocking areas; h) a gradient profile for all running lines, showing key geographical features and

distances; i) signal box notes (see Section 1.3); j) ground frame, gate box and automatic level crossing diagrams and notes

(where they are released, slotted or monitored by the signal box); k) control tables (see Section 3) - optional;


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l) other information to enable signallers to comply with local operating instructions.

Distances should be expressed in a manner that allows easy reference to the railway infrastructure.

5.2 Lockout Device Diagram The diagram required to be provided adjacent to each fixed trackside enabling device, in accordance with GK/RT0030, should be presented in a consistent manner for all protected areas with a common user. It should give a representation of the layout of the protected area that is geographically correct and orientated in relation to the user. Any movements that are not inhibited should be clearly stated, e.g. “Area covered by the lockout, except for the following movements: All right direction movements.”

5.3 Isolation Overlay This is a transparent copy of the faceplate which can be physically attached to a control panel, or an overlay displayed on a VDU, to remind the signaller that specific sections of route are barred to electric traction.

The necessary information is obtained from the electric traction engineer. They should be provided for 25kV and dual voltage electrified lines. See also GM/RT1006 for other isolation documents.

5.4 Signaller’s Route List This is a tabulation of all signalled movements, showing the required lie of all point ends located directly in the route, for use by the signaller in accordance with the Rule Book, Section F(i), when power operated points are to be operated manually, or when the points in route setting systems are to be set by individual point control devices.

A signaller’s route list is provided to assist the signaller when it is necessary to hand signal during times when it is not possible to set routes and clear signals in the ordinary manner. An updated list should be received at the signal box before altered signalling is commissioned.

The list may take various forms, according to the requirements of the infrastructure controller responsible for the signal box. The required form should be documented in the design specification. Examples include:

a) a large table associated with the control tables; b) a book of (preferably A4) sheets; or c) a set of cards (one per route).

Each individual item should be certified. For instance, in case (c) each card should be certified on the back, giving as a minimum the number, version and date updated for the source record (each sheet may comprise many cards), the issue date and the name of the records custodian.

The minimum content is mandated in GK/RT0026, but the actual requirement of the infrastructure controller responsible for the signal box should be written into the design specification, so as to facilitate the operations instructions appropriate to the signal box concerned.

If the operations instructions require the signaller to switch off the ARS sub-area, the sub-area to which the route belongs should be readily apparent to the signaller. Likewise, if special instructions are provided for electronic remote control areas, the type of remote control for the route should be apparent.



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The requirements should be applied in a consistent manner, using standard forms of words for special controls such as manually controlled level crossings, ground frames, slots, shunters and other releases. Other considerations include the method of protection against directly opposing routes and routes over diamond crossings, the setting of pre-set signals, and the benefits offered by split detection.

(Signaller’s route lists were regionally known as route failure cards, section ‘D’ charts, signalling failure instructions - points list, point setting tables and E4.9.5 cards.)

5.5 Operating Notice Diagrams This is a simplified layout plan (which need not be to scale) for publication in, or with, the signalling alterations section of the weekly operating notice.

An operating notice diagram is used by the infrastructure controller to publish signalling and permanent way alterations to traincrew and other personnel concerned. It should be supplied to the infrastructure controller by an agreed time to enable personnel compliance.

The diagram should be accompanied by the following information:

a) a description of the signalling alterations, including: new signal boxes being commissioned; old signal boxes being abolished; signal boxes assuming responsibility for a new area or lines; lines being abolished; type of signalling (unless track circuit block); and any other item not shown clearly on the diagram;

b) a table of junction signal applications, including: signal number; aspect type; indication; application (destination); and points reversed (where alternative routes); and

c) a standard symbols sheet, an extra of GK/RT0004 that may form the back cover of the notice.

(Operating notice diagrams were regionally known as section ‘C’ diagrams, signalling instruction notices, yellow notices and train crew notices).

5.5.1 Content Warning routes need not be separately identified, but all wrong road shunt routes should be shown. Where applicable, a table of flashing aspect applications should also be provided.

The operating notice diagram should only include the following information, using the symbols depicted in GK/RT0004. (If necessary, new signalling may be delineated with brackets or shown bold or in red.)

a) the affected lines extended as far as existing signals;

b) points (and their numbers when referred to in the table of junction signals), with ‘C&P’ to denote any that are clipped and padlocked;

c) in complex S&C, new lines and crossovers in bold or red lines;

d) stations;

e) the names of lines, sidings, junctions and platform numbers, in accordance with the sectional appendix (with arrows to show direction of main running movements, or the note “out of use”);

f) signal profiles, showing position light signals, route indicators and signal number, with prefix of fringe signal boxes (former numbers may be shown in brackets);

g) all telephones, although SPTs may be covered by a general note;


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h) stop boards stating the legend, and limit of shunt indicators, if necessary dimensioned to show standage;

i) distances between main stop signals, with isolated distant and banner repeating signals dimensioned to the associated stop signal;

j) Off, RA and CD indicators (showing how mounted) and RA, CD and TRTS plungers;

k) level crossings, in accordance with the sectional appendix, stating “CCTV” where applicable, (including user worked and footpath / bridleway crossings if equipped with telephones to the signal box), telephones, advance warning boards and drivers’ plungers;

l) AWS inductors, with applicable direction(s) on bi-directional lines, and cancelling indicators;

m) the length of new or altered sidings; and

n) depot facilities, such as train washer machines and shunter’s releases.

5.5.2 Exclusions The following items should not generally be shown:

• bridges (although tunnels and viaducts should generally be shown); • gradients; • FPLs; • detonator placers; • slots; • the number of levers at ground frames nor whether covered; • the normal aspect of signals, nor • other information not relevant to train crews.

5.6 Safety Diagrams Safety diagrams are required to warn personnel of the introduction of bi-directional signalling or changes in direction of traffic, so as to satisfy GO/RT3354.


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Part P

Dependability 1 Introduction

Dependability includes reliability, availability, maintainability and safety (RAMS), as described in GK/RT0201.

Any client specified dependability performance should be stated in the client remit and design specification (see Part C). These should be developed in conjunction with the infrastructure controller.

The means of developing and designing a signalling system to satisfy specified RAMS requirements is given in pr EN50126.

2 Reliability Reliability is the probability that an item can perform a required function under given conditions for a prescribed time without suffering failure. The client may specify the reliability performance of each sub-system. These may be expressed in terms of “mean time between failures” or “failure rate” of components or sub-systems. Alternatively, reliability requirements may be determined from the client’s required availability performance.

Individual components should be chosen with failure rates that fulfil the system reliability and availability requirements. Reliability is improved by use of some of the following techniques to reduce the fault rates of system components:

a) under-running; b) mid-life renewal; c) operationally tried and tested components / units with well defined

characteristics, including high security memories for storing of safety-related programs;

d) use of modern technology to develop long-life equipment, e.g. LED arrays in lieu of signal lamps; and

e) techniques to reduce complexity, such as modularization (clearly defined sub-units with simple interfaces); hierarchically structured circuit design; or manufactured and pre-tested circuit parts.

Measures of system reliability, such as mean time between failures, are concerned only with random hardware failures (in cases where failure of the total system is generally unpredictable) and do not include systematic failures. Further details of failure modes are given in Appendix B of GK/RT0206.

3 Availability Availability is the ability of a system to be in a state to perform a required function under given conditions. The client should generally specify the availability performance of the system. These may be expressed as a probability, such as “acceptable level of availability risk”, or in terms of “mean time between service failures” or “system downtime”.

3.1 System Options The design of the safety-critical and safety-related signalling systems should consider the following features, particularly to allow for the safe passage of trains under degraded conditions. Electronic systems, due to their flexibility, present the opportunity for incorporation of advanced facilities, such as:

a) multiple safety-related systems, for diversity, to ensure reversion to a safe state if the outputs fail to correspond;

b) multiple systems, for redundancy, to ensure continuity of operation on the failure of one path;



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c) immediate recognition of actual failures to initiate back up systems and make signallers or maintainers aware;

d) provision of uninterruptible power supplies;

e) allocation of functions so as to minimise disruption to train operations from a single sub-system failure or overcurrent protective device operation;

f) automatic switching to a degraded mode of operation if a particular subsystem or input fails, e.g. initiation of single route setting following the failure of flank protection, or stepping down of signal aspects to enable a train to approach a signal that would otherwise be extinguished;

g) reconfiguration to isolate failed equipment and permit other parts of the system to be reinstated;

h) automatic correction or reconfiguration of axle counters;

i) sequence proving of track section operation;

j) isolation of certain block systems to enable out-of-service resetting by the maintainer prior to restoration by the signaller, where the resetting presents a hazard (see GK/RT0027);

k) constant warning time devices for level crossings;

l) facilities to set restrictive controls on the equipment;

m) facilities to interrogate the system;

n) provision of essential fault diagnostic information;

o) monitoring and proving systems with a signaller’s alarm for safety-related functions;

p) where necessary to achieve the required availability level, a condition monitoring system to detect impending failures; and / or

q) computer aided diagnostic and simulation systems, where required.

3.2 Application The options listed in Section 3.1 may be achieved:

a) within the main signalling system; b) by the provision of a monitoring system(s); or c) by some combination of the two.

Further details of availability enhancement techniques are given in Appendix B of GK/RT0206.

4 Maintainability Maintainability is the probability that a given active maintenance action for an item under given conditions of use can be carried out within a stated time interval, when the maintenance is performed under stated conditions and using stated procedures and resources. The client should generally specify the maintainability performance of the system. These may be expressed in terms of “preventative maintenance time” and “mean time to restoration” for the system, or “mean time to replace” for individual components.

Maintainer’s facilities should be provided as required to meet the specified maintainability and availability performance. To justify the provision, the design authority may be required to produce:

a) the dependability performance achievable by the design; b) the constraints of use that affect the dependability;


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c) the maintenance programme requirements that ensure continued maintainability characteristics;

d) the maintenance planning support documentation (e.g. suppliers of spare parts, warranties, logistics details); and

e) a verifiable process by which the above details may be determined.

Details of maintainer’s facilities to be considered for interlockings are given in GK/RC0706, Part F.

Maintenance specifications for standard signalling equipment are given in GK/RH0750.

4.1 Features to Improve Maintainability Consideration of the following features in the design of signalling systems should result in improved maintainability:

a) duplication to provide facilities for certain preventative maintenance to be undertaken off-line, e.g. for power supplies;

b) facilities for on-line preventative maintenance;

c) accessibility of equipment;

d) as far as reasonably practicable, the removal of all maintainable equipment from proximity of the running line, i.e. into the green zone;

e) the location of certain vulnerable equipment in equipment buildings rather than apparatus cases;

f) the use of axle counters instead of track circuits on certain vulnerable sections of line, such as through tunnels;

g) facilities for rapid replacement of equipment, such as plug couplers or pre-formed cables;

h) the requirements of GK/RT0027, where the resetting of block systems following a failure presents a hazard to train operations;

i) adequate provision and location of spare equipment or system capacity, for immediate use;

j) perceived commercial availability of spare equipment that is operationally equivalent, for the life of the system;

k) monitoring and self diagnostic capability (see also Section 3.1);

l) the provision of suitable test equipment;

m) arrangements for suitably trained maintainers to be provided; and

n) security, or resilience to vandalism.

5 Safety Safety is freedom from unacceptable risk of harm to passengers, public and employees. (Risk is the product of the likelihood of a hazard and its severity. Hazard is the potential to cause harm.) Safety integrity is the degree of confidence that is required in a safety-related system and may be stated in terms of “dangerous failure rate” or safety integrity level (SIL). Further details of SILs are given in Appendix B of GK/RT0206.



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Risk may be expressed as “probability of fatality per annum”. Railtrack’s Railway Safety Case quotes upper and lower limits of tolerability of risk to passengers, public and employees, as well as potential equivalent fatality (PEF) figures which allow injuries to be expressed as a fraction of a fatality. Further details of risk tolerability are given in Appendix A of GK/RT0206.

Guidance on occupational safety is given below in Part Q, and system safety in Part R.


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Part Q

Occupational Safety 1 Construction (Design

and Management) Regulations

The Construction (Design and Management) Regulations 1994 (CDM Regulations) were introduced to reduce risks to health and safety associated with construction projects. These are deemed to include the excavation, construction, alteration, commissioning, maintenance, or recovery of the following:

a) any building; b) any steel or concrete structure, e.g. a signal post; c) a railway line; d) scaffolding; e) any similar structure; f) fixed plant, e.g. a signalling installation, where any work involves a risk of

falling more than two metres; or g) fixed services, e.g. electrical or telecommunications, generally associated with

any of the above structures.

As stated in GC/RT5210, where reasonably practicable, the requirements of the CDM Regulations should be applied to all signalling design and not just the elements listed above.

2 Design Requirements for Occupational Safety

The CDM Regulations place a duty upon designers. (Designers includes architects, consulting engineers, quantity surveyors, principal contractors and specialist subcontractors undertaking design specification, or the production of design details or bills of quantity.) Design authorities are required to undertake the following:

a) before commencing design, ensure that the client is aware of his duties under the regulations (e.g. to appoint a planning supervisor and principal contractor who must prepare the appropriate health and safety plans);

b) recognise health and safety risks, so far as is reasonable at the time the design is prepared;

c) wherever possible eliminate the risks by changing the design (i.e. designing them out) so far as it reasonably practicable, involving a proper exercise of judgement;

d) where risks cannot be reasonably avoided, control them at source by designing-in general protection, if this is within the designer’s influence;

e) where general protection cannot be reasonably designed in, consider the need for individual protection, e.g. personal protective equipment;

f) pass on information about the particular risks that remain and might be encountered during construction, maintenance, future alteration, or future recovery, by including the information in the design;

g) co-operate with the planning supervisor and all other design authorities;



1 7 2 R A I L T R A C K


h) be prepared to give to the client evidence of competence and adequate resourcing; and

i) when allocating work to another designer, assess their competence and resourcing.

3 Health and Safety Information

Railtrack should supply the design authority with all relevant information that can be reasonably obtained, such as hazard directories, sectional appendices (updated weekly), site access points, authorised walking routes, permissible train speeds, COSHH data sheets and the health and safety policy that is to be operated.

The health and safety plan should give safety arrangements for the project and should refer, for instance, to areas of limited clearance and whether red or green zone working is to be applied. The requirements are listed in GK/RT0201.

The design authority should provide adequate health and safety information with the design details to enable a competent contractor (i.e. installer, maintainer, or tester) to put appropriate precautions in place. These details should be passed to the planning supervisor for inclusion in the health and safety plan, or health and safety file which will be retained for the life of the installation.

The health and safety file is handed over to the infrastructure controller after completion of the project and should ideally be held on the premises to which it relates. It should contain (or reference) design records, operation and maintenance manuals, and any other information on risks to be managed during operation, maintenance, or future works on the completed infrastructure. The requirements are given in GK/RT0201.

4 Risk Assessment and Control

To avoid the possibility of professional negligence, it is essential that all risks are assessed and all decisions documented. This process is best accomplished within the design system, using the design specification or health and safety plan, but only requires key information to be recorded. Guidance on risk assessment is given in Part R.

Qualitative examples of the options available to designers to eliminate hazards or control risks are given in Figure Q1. These examples are illustrative only and are not exhaustive. Where hazards cannot be eliminated at source, additional information may be required in health and safety plans, and / or noted on design details to help installers manage the risks.

Hazard Eliminate at Source (Design Out)

Control: General Control: Individual

proximity of work site and installed equipment to the

• position equipment and / or work site in the green

• provide temporary fencing or permanent guard rails

• conduct track safety briefing


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R A I L T R A C K 1 7 3




running line, i.e. red zone or green zone

zone • prewire relocatable

equipment housings off site

• consider the provision of an equipment room instead of several apparatus cases

• specify the use of low maintenance materials and reliable equipment, to minimise the exposure of maintainers to lineside hazards (partial protection)

• install train activated warning system (partial protection)

• locate point machines, ground signals and signal post telephones on the cess side to provide access without crossing tracks (partial protection)

• provide remote indication of the location of failures and test points (or appropriate relays) in the green zone

• work to safety procedures, either under possession or with adequate provision of lookouts

restricted lineside clearance • relocate equipment away from such areas and away from tunnels, viaducts and retaining walls, etc.

• reposition signals to give safer access to SPTs

• provide warning signs (partial protection)

• provide special SPTs


• work only under possession

operation of construction plant fence areas where plant is to operate

operate plant only under possession, or follow safety procedures, e.g. make special provision for lookout warning with noisy plant

operation and maintenance of installed equipment

specify the use of low maintenance materials and reliable equipment, to minimise the exposure of maintainers to lineside hazards (partial protection)

be aware of operating and maintenance procedures, so they can be considered in the design

means of transportation of persons, equipment and materials from access point to work site

arrange work site to be adjacent to access point

show access points on signalling plans (partial protection)


• provide trolleys, etc. for use under possession

• provide lookouts for persons walking

other manual handing specify lightweight equipment • specify lifting lugs on heavy equipment

• provide lifting beams in equipment rooms where heavy equipment might have to be renewed

follow manual handling procedures

proximity of work site and installed equipment to overhead power lines or OLE

• position equipment work and plant movements away from danger (and at least 2.5m from structures bonded to the running rails)

• relocate the power lines

provide: • earthed screens • equipotential bonding • insulated barriers

work to safety procedures, permit to work, etc.

clearances from electrical equipment in equipment rooms

enclose all live equipment in cubicles

• enclose live busbars • provide adequate

clearances in gangways

• provide warning notices on live equipment

• ensure only trained personnel have access

Figure Q1 continued ...



1 7 4 R A I L T R A C K




fire • specify ZHLS materials • avoid storing flammable

substances on site

• design exit routes to be available at all stages of construction

• arrange early provision of warning notices and fire prevention systems / alarms

provide fire extinguishers

explosion design for sealed cells, UPSs, etc. to avoid the emission of hydrogen gas

provide well ventilated battery housings, away from electrical devices, such as fuses or links, that could create arcing

proximity of work site and installed equipment to conductor rails

• position equipment and / or work site away from danger

• gap the conductor rail

provide protective boarding (partial protection)

• work to safety procedures, permit to work, etc.

• provide rubber gloves, protective mats, conductor rail shield, etc.

protection from electric shock, both by direct contact and by indirect contact, and the use of a single earth to prevent dangerous touch potentials

use extra low voltage systems • provide adequate insulation or barriers

• design a single earth system with equipotential bonding as necessary

• provide adjacent clearly labelled isolation points with lock-off device and warning notices (partial protection)

• work to safety procedures, permit to work, etc.

• provide rubber gloves, protective mats, etc.

• provide residual current devices for the protection of personnel at work sites

overload of electrical equipment and cables

provide correctly rated excess current protection, i.e. fuses or circuit breakers

provide residual current devices for the protection of personnel at work sites, ensuring additional hazards do not result from red operation

lighting and working space avoid cramping equipment in confined spaces

provide adequate lighting and gangways

provide portable lamps and ladders etc.

hazardous substances • design for sealed cells, UPSs, etc. to avoid the use of battery acid

• position structures, underground services, etc. away from any contaminated land

provide warning notices (partial protection)

• provide goggles, face masks, etc.

• have COSHH data sheets available

noise, vibration, dust, or other environmental factors, such as treatment, cutting or drilling likely to generate hazardous fumes or dust

• specify materials prepared off site

• minimise the site cutting of concrete troughing, etc.

• specify materials that are safer to work

• provide adequate ventilation

provide face masks, ear protectors, etc.

falls from height, e.g. working from ladders, signal posts or telegraph poles, viaducts or bridges

• avoid placing equipment on bridges and viaducts

• specify equipment that can be lowered to ground level for maintenance

incorporate safety railings or parapets in the design

• provide safety harnesses • incorporate anchor points

in the design

buried services plan work site to be well clear of existing services

keep accurate records of buried services so they can be considered in the design

follow safety procedures when excavating

collapse during excavation, demolition, or erection of structures

design to minimise the number of undertrack crossings or cantilevered structures, etc. required

• use specialist contractors • allow for temporary

support in the design

provide hard hats, etc.

Figure Q1 continued ...


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R A I L T R A C K 1 7 5




tripping hazards locate all equipment in apparatus cases

• provide adequate walkways

• paint tripping hazards, e.g. disconection boxes, white

vandalism position equipment and / or work site out of sight

specify anti-vandal measures, e.g. polycarbonate lenses, glued cable troughing, armoured cable, etc.

novel equipment specify equipment designed for the required purpose

provide warning notices (partial protection)

train personnel in the correct use

changeover from existing to new equipment

design new system to be independent of existing

design stagework controlled changeover in accordance with testing procedures

Figure Q1 Examples of Qualitative Hazard Identification and Risk Control


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R A I L T R A C K 1 7 7


Part R

System Safety 1 Introduction

Some type of risk assessment to demonstrate functional safety should be used whenever departure from a Code of Practice is proposed, as described in GK/RT0206. The degree of detail in the analysis should reflect the degree of departure from the Code of Practice and the level of risk involved.

It should be demonstrated that any hazards identified present an acceptable risk to passengers, public or employees, so as to comply with Railtrack’s duty under its Railway Safety Case (RSC). Mitigation measures must be implemented for those hazards which present an unacceptable risk.

Similar risk assessments may also be performed where it is desired to improve the reliability, availability, maintainability or safety of an existing system or element.

It is generally simpler to analyse the system at signalling function level (i.e. signals, points, level crossings, etc.), but, where justified by the risk, a safety analysis at component level (such as relays and contacts) may be appropriate.

2 Risk Assessment An example of risk assessment is given in Figures R1 to R10, relating to automatic signal 103 on the layout provided in Figure R12. It should be noted that an actual risk assessment requires full calculations and reference to source information, which have not been given here for the sake of simplicity. All values quoted are illustrative only.

2.1 Hazard Log A simple hazard log should be created using failure modes, effects and criticality analysis (FMECA), or similar techniques. Further information is given in BS 5760: Part 5.

All hazards should be identified and logged. Creative methods of hazard identification, such as brainstorming, should be used for novel applications. The ranking obtained may be used to select the hazards that require further analysis. The range of values for frequency (F) and severity (S) should be individually defined, for example:

F=1 Less than 10 yearly S=1 Minor injury F=2 5 to 10 yearly S=2 Major injury F=3 1 to 5 yearly S=3 Multiple major injuries F=4 Monthly to yearly S=4 Single fatality F=5 Daily to monthly S=5 Multiple fatalities

An example of a hazard log is shown in Figure R1. Wrong side failures (WSFs) have been identified in the figures, but note that right side failures also give rise to hazards and have, by definition, a great frequency.



1 7 8 R A I L T R A C K


Ref. No.

Hazard Description Estimated Frequency

F

Estimated Severity

S

Hazard Ranking

F x S

Remarks

1 Train SPADS signal. 3 1 3 Possible WSF of distant signal (unlikely), isolation of AWS, poor visibility, or driver distraction. Likely to be low speed run-by. Protected by banner 105BR.

2 Signal off when train in section (WSF).

1 4 4 Possible WSF of a track section. Could result in collision with train in platform.

3 Signal comes off momentarily when train passes from EK to EL track (WSF).

3 1 3 Possible interface problem between transmission systems. Unlikely to occur at the same time as next train approaching (headway does not allow).

4 Signal not displaying red aspect when signaller’s replacement controls on (WSF).

3 2 6 Possible WSF of transmission system. Could result in fatality of track worker(s).

5 Signal off when signal 105 ahead on and signal or banner lamp extinguished (WSF).

1 3 3 Possible WSF of signal circuit. Could result in a serious SPAD at signal 105.

6 Signal off when detection failed on 705 points in overlap (WSF).

2 1 2 Possible WSF of detection circuit. Could result in a derailment if the train SPADS signal 105.

7 Signal green when signal 105 ahead at red (WSF).

1 1 1 Minimal consequence, as braking distance available from 105BR banner to signal 105 ahead.

8 Unable to obtain proceed aspect.

4 1 4 Right side failure. Hazard from service disruption and instructing trains to pass signal at danger (or out).

9 Red lamp out when controls on. 3 1 3 Protected by signal in rear held at red, but hazard from trains proceeding at caution through long section from previous signal box.

10 Signal replaced in front of train. 3 1 3 Possible detection failure when 705 points swung in the overlap. Hazard from emergency braking.

Figure R1 Hazard Log for Auto Signal No.103

2.2 Causal Analysis Where necessary, a fault tree should be used to more accurately determine the probability of each hazard as an annual frequency. The symbols used should be defined on the drawing (see BS 5760: Part 7).

The probabilities of the basic events (shown numbered in the examples) may be obtained from such sources as:

• the train working timetable; • component failure statistics (gathered in accordance with GK/RT0106); • failure modes for different types of component, listed in prENV50129; • historical operating experience of established systems.

The fault tree connects events by means of ‘AND’ gates and ‘OR’ gates. The probability of the top event may be obtained mathematically by summing the probabilities at OR gates and taking the product at AND gates.

Hazard 4 in the example is analysed in Figure R2, and hazard 8 in Figure R3.


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R A I L T R A C K 1 7 9


Figure R2 Causal Fault Tree for Hazard 4

2.3 Consequence Analysis Having calculated the probability of the significant hazards occurring, an event tree may be used to determine the likelihood of an incident arising from each hazard. The frequencies of the consequences may be apportioned using similar calculations to those used for causal analysis.

Hazard 8 in the example is analysed in Figure R4.

Obscuredlens

WSF of signal postreplacement switch

Failure of signalman’sreplacement controls

Signal not displaying red aspect whenreplacement controls are on

Lightingpowerfailure

Red lamp notvisible

High resistancecomponent

Rupturedfuse

Red lampfailure

WSF atsignalbox

Signalman failsto operate

correct device

WSF of signalcontrol circuit

WSF oftransmission

system

WSF ofsignalman’s

control device

Signalman failsto observeindication

Contactfails tobreak

Relay fails todrop

Earth faultbridges outcontact(s)

Short circuitbridges outcontact(s)

Contactfails tobreak

Relay fails todrop

Earth faultbridges outcontact(s)

Short circuitbridges outcontact(s)

19181716

1514131211

109876

54

&

See Figure R3 for Key

3



1 8 0 R A I L T R A C K


Figure R3 Causal Fault Tree for Hazard 8

Signal control relaynot energised

Unable to obtainproceed aspect

Failure oftransmission

system

Failure ofsignal box

circuit

Lamp notvisible

Green lamp notvisible

Signal control-led to green

&

Signal control-led to yellow

Yellow lampnot visible

2120

11

19

1615

1413

12

1098

110Vpowerfailure

Obscuredlens


Rupturedfuse

Green lampfailure

7654

3

21

&

110Vpowerfailure

Obscuredlens


Rupturedfuse

Yellowlamp failure

4

Relayfailure


50V powerfailure

Bannersignal105BRfailure

Failure ofsignalman’sreplacement

controls

Lampfailure onsignal 105

5

110Vpowerfailure

T/J failure Rupturedfuse

4

Detectionfailure onpoints 705

Highresistancecomponent

Relayfailure

Failure ofsignalman’s

control device

Signal boxpowerfailure

Systemfailure

Failure ofamplifier

Signal boxpowerfailure

&

KEY

AND gate

OR gate

Basic event

Event detailedelsewhere in fault tree

Event developed onanother fault tree

17

Tracksectionfailure

Track relayde-energised

Tracksection

obstructed

18


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R A I L T R A C K 1 8 1


Figure R4 Consequence Event Tree for Hazard 8

2.4 Loss Analysis The hazard frequencies and the likelihood of an incident arising may be further analysed in terms of the safety and financial losses incurred, so as to avoid expenditure on mitigation measures where the cost would be grossly disproportional to any improvement gained.

Yes: prob=0.3 No: prob=0.7

Signal 105 ahead is off


Signal 105 ahead is alight


Track section EK is occupied


Telephone to signal box is operational


Handsignaller is appointed

Unable to obtainproceed aspect


Train does not proceed until safe to do so


Train stops before striking train ahead

Note:The causes of this hazard maytypically be apportioned as follows,using calculations based on Figure R3:Lamp failure of this signal 0.05Track section failure 0.5Track section occupied 0.05Signal 105 lamp failure 0.05Banner 105BR failure 0.1Points 705 detection failure 0.1Power failure 0.1Control circuit/system fault 0.05

TrainSPADs

signal 105

Traincollides withtrain ahead

Traindelayed10 mins.


Driver misses signal ahead


Banner signal 105BR is operational

Near miss:furtherdelay

Apportionment ofincidents arisingfrom this hazard: 0.00130.00370.99 0.0024



1 8 2 R A I L T R A C K


The value of preventing a fatality (VFP) and potential equivalent fatality (PEF) figures can be found in Railtrack’s RSC.


Incident Nature of loss

Near miss Fatality of track worker

Derailment of train

Assumptions

Cost of delay @ £100 per minute

£1,000 £5,000 £50,000

Damage to assets £50,000

Harm to employees £800,000 £4,000 VPF = £0.8m

Harm to passengers £4,000 1 fatality = 200 minor injuries (PEF)

Total loss per incident £1,000 £805,000 £108,000

Probability of incident (frequency per annum)

0.003 x 0.5 0.003 x 0.25 0.003 x 0.25 Frequency of hazard 4 during a possession is 0.2 x 0.015 p.a. Consequences are apportioned 0.5:0.25:0.25 (say).

Loss per annum £1 £604 £81 Total annual loss = £686

Figure R5 Loss Analysis for Hazard 4 (Signal not displaying red aspect when signaller’s replacement controls on)

Incident Nature of loss

Train delayed 10 mins.

Near miss: further delay

Train SParts signal 105

Train strikes train ahead

Assumptions

Cost of delay @ £100 per minute

£1,000 £2,000 £10,000 £50,000

Damage to assets £1,000 £50,000 SPADing train runs through 708 points (with no conflicting route) or runs into sand drag.

Harm to passengers @ £0.8m VPF

£4,000 £800,000 1 fatality = 200 minor injuries (PEF)

Total loss per incident £1,000 £2,000 £15,000 £900,000

Probability of incident 1.5 x 0.99 1.5 x 0.0037 1.5 x 0.0024 1.5 x 0.0013 Causal analysis shows frequency of hazard 8 to be 1.5 per annum (say).

Loss per annum £1,485 £11 £54 £1,755 Total annual loss = £3,305

Figure R6 Loss Analysis for Hazard 8 (Unable to obtain proceed aspect)

2.5 Options and Impact Analysis All potential risk mitigation measures should be identified, which can either reduce the risk of occurrence of the hazard, or mitigate the severity of the consequences. The causal and consequence analyses may then be revised to give a reduced hazard frequency for each option. By repeating the loss analysis, the financial benefit of loss mitigation may be obtained for each option to allow direct comparison.

Implementation costs should be discounted over the life of the option, taking changed maintenance costs into account, so as to give an annual cost for the mitigation measure.



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R A I L T R A C K 1 8 3


Risk mitigation options

Hazard frequency

from causal

analysis

Total

annual loss

Losses per annum

mitigated (total

BENEFIT)

Implement-ation cost

Total discounted COST per

annum

Remarks

- Existing situation 0.0030 p.a.

£686 - - -

1 Improve lamp reliability using LED array

0.0022 p.a.

£503 £183 £5,000 £150 Benefit > cost. Reduced maintenance.

2 Remove signal post replacement switch

0.0022 p.a.

£503 £183 £1,000 £25 Benefit > cost. Reduced maintenance.

3 Make transmission system SIL 4, or duplicate channels

0.0026 p.a.

£595 £91 £3,500 £700 Cost > benefit. Discounted over 5 years.

4 Prove replacement effective and signal alight in indication

0.0022 p.a.

£503 £183 £3,500 £150 Benefit > cost. Increased maintenance.

Note: all circuits already double cut to protect against earth faults.

Figure R7 Cost-Benefit Analysis of Risk Mitigation Options for Hazard 4

Risk mitigation options

Hazard frequency

from causal

analysis

Total

annual loss

Losses per annum

mitigated (total

BENEFIT)

Implement-ation cost

Total discounted COST per

annum

Remarks

- Existing situation 1.50 p.a. £3,305 - - - 1 Improve lamp reliability

using LED array 1.25 p.a. £2,754 £551 £5,000 £150 Benefit > cost.

Reduced maintenance. 2 Arrange stepping down of

aspects on lamp failure 1.35 p.a. £2,974 £331 £10,000 £500 Cost > benefit.

Increased maintenance. 3 Improve track reliability

using axle counters 0.80 p.a. £1,763 £1,542 £15,000 £3,000 Cost > benefit.

Discounted over 5 years. 4 Options 1 & 2 together (not

independent) 1.20 p.a. £2,644 £661 £15,000 £650 Marginal benefit.

Note: full SPAD mitigation is already installed at 105 signal.

Figure R8 Cost-Benefit Analysis of Risk Mitigation Options for Hazard 8

2.6 Compliance with Legal Duty It should be demonstrated that all risks to passengers, public and employees are acceptable, so as to comply with Railtrack’s duty under its RSC. Risk mitigation measures should be implemented to ensure that the total risk to each group of people complies with the following requirements, as described in Appendix A of GK/RT0206:

a) the risk must not be intolerable (above the upper limit of tolerability);

b) tolerable risks must be reduced to be as low as reasonably practicable (ALARP), i.e. until the cost of risk reduction is grossly disproportional to any improvement gained; and

c) if the risk is below the lower limit of tolerability, it must remain negligible.

The upper and lower limits of tolerability and a benchmark target are published in Railtrack’s RSC for each group of people.

Analysis involves summing the risks for each group of people at risk for all hazards associated with the function under consideration. The example in Figure R9 considers employees, who, at signal 103, are only significantly affected by Hazard 4.



1 8 4 R A I L T R A C K


Hazard 4 (signal not displaying red aspect when signaller’s replacement controls on) Risk mitigation options

Probability of the

hazard occurring

per annum

a

Likelihood of workers being on the track

b

Likelihood of the

hazard causing 1

fatality

c

Number of

workers exposed to risk

d

Probability of one

equivalent fatality p.a. e = axbxc

d

Employees limits of

tolerability from

Railtrack’s RSC

f

Employees limits of

tolerability associated

with this hazard

g

Risk lies in region

h - Existing situation 0.0030 0.2 0.25 20 7.5 x 10-6 Intolerable

1 Improve lamp reliability using LED array

0.0022 0.2 0.25 20 5.5 x 10-6 Intolerable

2 Remove signal post replacement switch

0.0022 0.2 0.25 20 5.5 x 10-6 10-3 to 10-6 10-6 to 10-9 Intolerable

3 Make transmission system SIL 4, or duplicate channels

0.0026 0.2 0.25 20 6.5 X 10-6 Intolerable

4 Prove replacement effective and signal alight in indication

0.0022 0.2 0.25 20 5.5 X 10-6 Intolerable

Residual risk when all options implemented

0.0002 0.2 0.25 20 5 x 10-7 10-3 to 10-6 10-6 to 10-9 Tolerable

Figure R9 Demonstration of ALARP for Employees Group

It is necessary to consider the risk to one of the individuals most at risk. The probability of one equivalent fatality per annum is given by: a x b x c. The probability of an equivalent fatality happening to a particular member of the group most at risk (column e) is given by that figure divided by the number of workers sharing the risk (d), the typical number of workers concerned.

Column f gives the limits of tolerability identified in Railtrack’s RSC for employees (generally trackside workers). Column g makes allowance for the other hazards over which the risk budget has to be shared. In this example, if the 20 workers sharing the risk work within the protection of 100 different signals and a signal being off when the signaller had replaced it represented one tenth of the total risk to which they were subjected at work, then the column f figure would have to be reduced by a factor of a 1000 to give the column g figure.

The region in which the risk lies (column h) can be determined by comparing column e with column g. In this example, all four risk mitigation options have to be implemented, whatever the cost, so as to reduce the risk below the upper limit of tolerability.

It has been assumed here that the results of each of the four options are independent of one another. However, it is generally better to revise the causal and consequence analyses to obtain new hazard probabilities for any proposed combination of measures.

Further risk reduction should be considered to reduce the risk to ALARP.

The example in Figure R10 considers passengers, who, at signal 103, are significantly affected by five of the hazards.


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R A I L T R A C K 1 8 5


Existing hazards at signal 103

Probabil-ity of the hazard occurrin

g per annum

a

Proportion of trains that are

passeng-er trains

b

Likelihood of the hazard causing

one fatality

c

Number of pass-engers

exposed to risk

d

Probability of one equivalent

fatality per annum

e = axbxcd

Passenger limits of

tolerability from

Railtrack’s RSC

f

Passenger limits of tolerability associated with this

hazard g

Risk lies in region

h 1 Train SPADs signal 0.2 0.5 Nil 1000 0

2 Signal off when train in section

0.01 0.5 0.05 (say) 1000 2.5 x 10-6

3 Signal comes off momentarily when train passes IRJ

0.2 0.5 Nil 1000 0

4 Signal not displaying red aspect when signaller’s replacement controls on

0.2 x 0.015

0.5 0.25 1000 3.8 x 10-7

5 Signal off when signal ahead on and signal or banner out

0.01 0.5 0.05 (say) 1000 2.5 x 10-7

6 Signal off when detection failed on 705 points in overlap

0.1 0.5 Nil 1000 0

7 Signal green when signal 105 ahead at red

0.01 0.5 Nil 1000 0

8 Unable to obtain proceed aspect

1.5 0.5 0.0024 + 0.0013 200

1000 9.8 x 10-7

9 Red lamp out when controls on

0.2 0.5 Nil 1000 0

10 Signal replace in front of train

0.2 0.5 0.05 (say) 200

1000 2 x 10-8

Total risk of passenger fatality

4.1 x 10-6 10-4 to 10-6 2 x 10-7 to2 x 10-9

Intolerable

Residual risk when neces-sary options implemented

1.0 x 10-7 10-4 to 10-6 2 x 10-7 to

2 x 10-9

Tolerable

Figure R10 Demonstration of ALARP for Passengers Group

The probability of one equivalent fatality per annum is given by: a x b x c. The probability of an equivalent fatality happening to a particular passenger (column e) is given by that figure divided by the number of passengers sharing the risk (d). This number is the number of passenger trains per annum (say 5000) multiplied by the average number of passengers (say 100) divided by the number of journeys per annum for a regular commuter (generally taken as 500).

Column g makes allowance for the hazards over which the risk budget has to be shared. This is the passenger limits of tolerability from the RSC multiplied by the proportion associated with hazards from this type of signal (say 10%) and the fraction of the average journey over which the hazard applies (say 2%).

Further risk reduction should be considered to reduce the risk to ALARP.

3 Documentation A copy of the safety analysis or risk assessment report should be held for the life of the installation on the health and safety file and should be referenced on an explanation or reference sheet at the front of the design details.

Where the risk assessment requires special safety features for risk mitigation, each instance should be identified on the explanation or reference sheet.

Where necessary, additional documentation should be provided to explain the purpose of particular circuitry features, as shown in Figure R11.



1 8 6 R A I L T R A C K


Figure R11 Typical Explanation of Circuitry Features for 103 GR Circuit at the Interlocking

Components Fuse 103YR

105ECPR

EKT2PR

ELT2PR

705OSR

103GR

103GR

Type(see GK/RT0330)

BS 7143 amp

931front

contact

933front

contact

933front

contact

931front

contact

931front

contact

934front

contact

934coil (slowrelease)

Quiescent state intact up up up up down up up103 GR requires intact up up up up up when

pointsmove

up for st ickpath

Notes #1 #2 #3 #4 #5 #6 #7 #11Components 705

RW KRDH

T2PRType(see GK/RT0330)

931front

contact

933front

contactQuiescent state parallel branch 1 down up103 GR requires up when

pointsreverse

up whenpoints

reverseNotes #8 #9

Components 705NW KR

Type(see GK/RT0330)

931front contact

Quiescent state parallel branch 2 up103 GR requires up when points normalNotes #10#1 50V internal supply.#2 Signaller’s replacement by TDM (duplicated channels) from signal box.#3 105 ECPR includes 105BR GZR for banner proving.#4 Same T2PR that controls 105 temporary approach control. DC track circuit requires one slow pick up TPR.#5 EL is overlap track circuit. DC track circuit requires one slow pick up TPR.#5/9 Analysis of joint hopping in normal and wrong directi ons, with these combinations of repeat relays, shows

acceptable timing for the permissible speed.#6 OSR relay circuit has been modified to correct timing problem when changing over. Holds up for 5 secs.

whilst points move.#7 Stick path to maintain GR whilst points move.#8/10 Detection of facing points in the overlap.#9 HVI track circuit requires two slow pick up TPRs. DH track is required clear when 705 points are reverse. A

contact is also required in series with 705 RWKR in 705 WKLJR circuit (which is in 705 OSR).Detection of 707 flank points normal (which are also facing points for swinging away a conflicting overlap),when 705 points are reversed, has been omitted here, because the probability of hazard 8 (Figure R1) wouldthereby be increased. Detection at time of setting only would increase the complexity/reliability of the circuitunjustifiably. See the control tables.

#11 Auto signal 103 HR is a line circuit fed over front contacts of 103 GR. This non-standard GR is required toprovide the stick feature, with a slow release coil to hold up whilst detection and OSR contacts change over.See transit time calculation.

103GR

705OSR

ELT2PR

EKT2PR

105ECPR

103YR 103 GR

DHT2PR

705RW KR

705NW KR


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Figure R12 Signalling Layout to Illustrate Examples (not to scale)


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References Note: The references are correct at GA/RM6501, Issue No. 14, at which time the documents shown in italics are in draft status, but they are included as their production is concurrent with this Code of Practice.

Railtrack’s Railway Safety Case

Railway Group Standards

BR13422 50Hz Single Phase A.C. Electrification - Immunisation of Signalling and Telecommunications Systems against Electrical Interference (to be replaced by GK/RT0132)

GC/RT5011 Switch and Crossing Systems GC/RT5210 Safety Management of Construction Activities Within the Railway Environment GH/ZC0002 Safety Terminology GK/RC0706 Signalling and Operational Telecommunications Design: Technical Guidance GK/RC0752 General Information on Track Circuits GK/RC0762 Track Circuit Actuator Interference Detector GK/RC0821 Siting Requirements for Lineside Apparatus Housings GK/RH0710 Signalling Design Handbook GK/RH0750 Signalling Maintenance Specifications Handbook GK/RT0002 Glossary of Signalling Terms GK/RT0004 Symbols for Use on Signalling Plans and Sketches GK/RT0005 Safety Related Colours for Signalling Application GK/RT0007 Alterations to Permissible Speeds GK/RT0009 Identification of Signalling and Related Equipment GK/RT0010 Management of Signalling Communications Systems GK/RT0011 Train Detection GK/RT0016 Automatic Warning System of Train Control (AWS) GK/RT0017 Trainstops GK/RT0025 Signalling Control and Display Systems GK/RR0026 Signalman’s Route Lists GK/RT0027 Resetting and Restoration to Service of Signalling Systems GK/RT0029 Train Activated Warning Systems GK/RT0030 Signalling Lockout Systems for the Protection of Personnel On or Near the Line GK/RT0031 Lineside Signals and Indicators GK/RT0032 Lineside Signal Aspect Sequences GK/RT0033 Lineside Signs GK/RT0034 Lineside Signal Spacing GK/RT0035 Layout of Lineside Signals GK/RT0036 Transition between Lineside Signalling Systems and Other Systems of Train Control GK/RT0037 Signal Sighting GK/RT0038 Speed Restrictions GK/RT0039 Semaphore and Mechanical Signalling GK/RT0040 Cab Signalling Systems GK/RT0041 Track Circuit Block GK/RT0042 Absolute Block GK/RT0044 Permissive Working GK/RT0051 Single Line Control GK/RT0054 Radio Electronic Tokenless Block GK/RT0060 Interlocking Principles GK/RT0061 Shunters Releases, Ground Frames, Switch Panels and Gate Boxes GK/RT0062 Control of Points GK/RT0063 Approach Locking and Train Operated Route Release GK/RT0065 Train Operated Points GK/RT0070 Level Crossings GK/RT0078 Overrun Protection and Mitigation GK/RT0101 Competence Standards for S&T Staff GK/RT0103 Management of Signalling Design Records GK/RT0104 Policy for Approval of Signalling Equipment GK/RT0105 The Transmission of Safety Related Information GK/RT0106 Safety Management of Signalling Failures



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GK/RT0110 Outline Project Specification (OPS) for Signalling Schemes GK/RT0115 Correlation of Signalling Records before Design Alterations GK/RT0116 Assessment of Signalling Systems before Design Alterations GK/RT0170 Asset Management for Safety of Signalling & Operational Telecommunication Systems & Eqmt GK/RT0201 Signalling Design: Production GK/RT0202 Signalling Design: Control Tables GK/RT0205 Symbols for Signalling Circuit Diagrams GK/RT0206 Signalling and Operational Telecommunications Design: Safety Requirements GK/RT0213 Signal Cable Equivalent Sizes GK/RT0221 Signalling Works Testing GK/RT0231 Signalling Maintenance Testing GK/RT0251 Track Circuits GK/RT0252 Minimum Requirements for the Bonding of Track Circuits GK/RT0330 Plug-In and Interchangeable Railway Signalling Equipment GMRT1006 Electrification Isolation Documents - Production and Modification GM/RT1103 Mechanical Protection and Marking of Buried Services GO/OT0018 Provision of Operations Instructions for Signal Boxes and Other Locations GO/RT3000 Master Rule Book GO/RT3270 Route Acceptance of Vehicles GO/RT3354 Requirements for the Management of Personal Track Safety GS/IH1D20 Electrical Wiring: Alterations to an Existing Installation GT/EH H802 Standard for Telecommunication Wiring and Terminations Specifications and Standard Drawings BR829 Plugboard for Miniature Relays BR1615 Relocatable Equipment Buildings for S&T Use BRS-SM440 Signalling Equipment Framework - Index of General Arrangements BRS-SW67 Standard Free-Wired Interlocking Typical Circuits Interlocking Systems AEI-GRS Associated Electrical Industries - General Railway Signal: Route Relay Interlocking and Geographical Interlocking Systems E10k BR (Western Region) Typical Circuits in the E10,000 drawing series SGE/AGS/GEF General Electric Company (now Alstom) Geographical Interlocking System RT Railtrack Line Typical Circuits (a development of BRS-SW67) ScR BR (Scottish Region) Geographical Interlocking System SGE Siemens & General Electric Railway Signals Ltd. Route Relay Interlocking System SSI GEC-GS/WBS/BRB Solid State Interlocking System SW67 BRB Free-Wired System for Route Relay Interlockings to BRS-SW67 WBS Westinghouse Brake & Signal Co. (now Westinghouse Signals Ltd.): Route Relay Interlocking and Westpac Geographical Interlocking Systems British Standards BS 88 Cartridges and Fuses for Voltages up to and including 1000 Volts AC or 1500 Volts DC BS 308 Engineering Drawing Practice BS 469 Specification for Electric Lamps for Railway Signalling BS 714 Specification: Cartridge Fuse-Links for Use in Railway Signalling Circuits BS 3939 Graphical Symbols for Electrical Power, Telecommunications and Electronic Diagrams BS 4778 Quality Vocabulary BS 5760 Reliability of Systems, Equipment and Components BS 7671 Requirements for Electrical Installations (IEE Wiring Regulations)


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European Standards and Pre-Standards pr EN50126 Railway Applications: The Specification and Demonstration of Reliability, Availability,

Maintainability and Safety (RAMS) pr EN50128 Railway Applications: Software for Railway Control and Protection Systems ENV 50129 Railway Applications: Safety Related Electronic Systems for Signalling IEC 1508 Functional Safety: Safety Related Systems Legislation and HSE/HMRI Guidance Construction (Design and Management) Regulations 1994 (CD Regs) Electricity at Work Regulations 1989 Electromagnetic Compatibility Regulations 1992 (EMC Regs) Health and Safety (Safety Signs and Signals) Regulations 1996 HSE/HMRI Guide to the Approval of Railway Works, Plant and Equipment 1994 Provision and Use of Work Equipment Regulations 1992 Railway Safety Principles and Guidance 1995 (RSPG)
