scort/trb rail capacity workshop - jacksonville florida1 1 a primer on capacity principles new...

SCORT/TRB Rail Capacity Workshop - Jacksonville Florida

1SCORT/TRB Rail Capacity Workshop

- Jacksonville Florida 1

Rail Capacity Workshop A Primer on

Capacity Principles New Technologies Public Sector Needs

22 September 2010 1SCORT/TRB Rail Capacity Workshop

- Jacksonville Florida


22

Signal and train control functions Train control and dispatching Signal systems and equipment Capacity effects

Part 2: Conventional Signaling and Train Control Technologies- A Primer

22 September 2010


3

Signal and Train Control Functions

Ensure Safety Collision Prevention Over speed prevention (some systems)

Train operations management Set or authorize routes Manage train priorities

Advanced train control systems supplement and enhance, but do not replace these

functions22 September 2010




Facilities and Installations

Central office Dispatchers desks (work stations) Remote switching (where available) Track layout displays Support software

Office to field communications (voice radio, “code line”) Field installations

Wayside signals Switches – powered and manual Block systems Track circuits Interlockings – prevent conflicting signal and switch settings Track-train communications (where applied)

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Track Capacity Effects

Track capacity depends on the technical features of office and field systems, especially: Block system types (manual, automatic, CTC) Block lengths Use of track circuits for train detection Switch control – powered or manual Train speeds – freight and passenger

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Manual Block System (MBS)

Station A Station B

Dark Territory

Authority Limit

Manual Generation of Authorities Voice Transmission & Repeat (3-5 mins) Voice Location Reporting & Authority

Release Manual Operation of Switches by Crew Low Capacity Operation – e.g. branch lines

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Station A Station B

Automatic Block Signals

Similar to MBS, except Automatic Signals Protect Rear of Train

Roll up of Authority Automatic detection of train using track circuits

Higher Capacity Operation – applied to lower traffic main lines

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MBS With Automatic Block System (ABS)




Consists of Signals & Switches operated by central dispatcher

Major advantage is avoiding manual switch delays

Supervisory OfficeControl and/or Indication

Remote Controlof Switches / Signals

Centralized Traffic Control

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Authority conveyed by Signal Indication Track Circuits convey train location to

dispatcher Block system protects train in block Much higher capacity Better train performance Applied to most higher capacity main lines on

US freight network outside terminal areas

Centralized Traffic Control (cont)

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Spe

ed

LoadedFreight

PassengerOr Commuter

Higher SpeedPassenger

Block Design Distance

Braking Curves – Mixed Freight and Passenger Traffic

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Block length is a function of freight train braking Typically 2 – 3 miles length




Block A5

Signal A4Train 2

Block A3

Directionof Travel

Signal A1

Block A1

Train 1Signal A3 Signal A2

Block A4 Block A2

Block is occupied by train

Normal Speed

Zero SpeedCaution Speed

NormalSpeed

NoCode

G Y R G

Block length fixed by maximum speed, civil limits, grade, and worst train braking distance.

Wayside Signal Spacing

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Additional aspects provide finer control of train movement, at additional cost and complexity. Trains operating at different

speed limits may require different rules.

Block A6

Signal A5Train 2

Block A3

Signal A1

Block A1

Train 1Signal A3 Signal A2

Block A5 Block A2

Normal SpeedZero

Speed

G/RSignal A4

Y/G

Block A4

G/RR/R

Y/R

CautionSpeed

NormalSpeed

NoCode

AdvancedApproach

Block is occupied by train

Signal Spacing - Options

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Automatic Systems Most conventional systems rely on

engineer compliance with signals and operating rules

Automated systems provide in cab displays and may enforce compliance

Principal systems are: Automatic Train Stop – ATS

Enforce braking if engineer fails to respond to signals

Normally 8 second delay before enforcement Automatic Cab Signals - ACS Automatic Train Control – ATC Civil Speed Enforcement – NEC and some NJT

only22 September 2010




Aspect transmitted display in engineer’s cab

Brakes apply automatically if authority is exceeded

Used on NEC, LIRR, MNCR, NJT, limited elsewhere

Direction of TravelTrain

Signal

SignalData

DataCode

CodeGenerator

Code Transmission in Rails

Code Pick-UpCoils

Speedo

BrakeInterface

Processor Signal Data

Driver’s Panel

Two types:

• Intermittent• Continuous

Cab Signals

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No changes can occur while trainis outside of limited intervals.

• Speed authorization is passed to train at limited intervals, typically at signal locations.• Train stores information until next authorization is received.

Intermittent , ATS, ACS, ATC

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• Speed authorization is continuously updated to vehicle.• Changes in speed authority can be made at any time, and are visible to operator immediately.• Capability to increase traffic; immediate recognition of aspect upgrades allow quicker response.• Loss of signal is most restrictive, stopping train.• Train requires no ‘memory.’

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Continuous ATS, ACS, ATC




Signal A2Signal A4 Signal A1Train 2 Train 1G Y R G

Signal A3

Without ATP, Train 2 continues to slow throughout block, even though Train 1 proceeds past Signal A1.

Y

Signal A2Signal A4 Signal A1G Y R G

Signal A3

With ATP, Train 2 can resume normal speed as soon as Train 1 proceeds completely past Signal A1, increasing capacity

Y G

Train 2 Train 1

Advantages of Continuous Automatic Systems

22 September 2010




Home Signal - Controls entrance into interlockings.Most restrictive display is “STOP.”

Distant Signal - Last automatic signal beforea home signal. Most restrictive display is

usually “Stop and proceed.”

Intermediate Signals - Non-controlled signals other than distant signals –Aspect display cascades from next signal aspect. Most restrictive

display is “Stop and Proceed.”

Types of Signals

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Signals indicate authorized speed:

Speed Signaling Displays speed at this and next signal Turnouts speeds displayed where

applicable Requires many signal aspects Applied on the NEC

Types of Signal – Speed Signaling

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Route Signaling Displays 3 or 4 Aspects

Clear , (double Approach), Approach to Stop & Stop

Diverging route, where applicable Turnout speed is shown in timetable

Signaling indicates selected route:

Signal Systems – Route Signaling

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Minimum warning time by state regulation or FRA is 20 seconds.

>20 Seconds

Highway Crossing Protection

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20 seconds – Any Speed

Constant Warning - Grade Crossing PredictorMeasures train speed and adjusts warning for

constant warning time

20 seconds = 2933 feet at 100 MPH

20 seconds = 733 feet at 25 MPH

Fixed Track Circuit Approach - Varies with train speed

80 seconds at 25 MPH


22 September 2010




Highway traffic signal pre-emption at nearby intersections.

When train approaches, highway traffic signals prevent turns towards crossing , while allowing cars to clear

crossing.


22 September 2010

scort/trb rail capacity workshop - jacksonville florida1 1 a primer on capacity principles new...

Documents

train control technologies

train location

rear of train

train detection switch

higher capacity main

equipment capacity effects

manual train speeds

block system types manual