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“Non-interlocking work”, whenever we hear these words, trails left by it in past,immediately comes to our mind as a nightmare. Introduction of manual working evenduring a small failure of signaling gears on any of the section of NCR makes a chainaffect on operations, besides safety being dependent up a single human being. Non-Interlocking enlarges this to a complete station yard and situation becomes furthermore and very complex when yard remodeling is also involved, which forces inductionof multiple agencies. Traditionally practice of giving free Home Signal bypassingsetting of Point position & Vehicle Detection Devices and authority for Starter/Advanced Starter signals is going on as the accepted means for NI working. Settingup of gumties sometimes even upto 20 for setting and clamping of Points, exchange

of Private Numbers between gumties and then issue of authority are the activities which get introduced as thedefault procedures of this type of working.

1.0 Repercussion of this conventional NI working are:-1.1 Heavy impact on operations minimum 50 minutes to 1 hrs is taken to pass a train at the station. Lot of

time is consumed in communication between different gumties, sometimes wrong authority, trainsonce coming to a halt taking time to restart as exchange of signals between guard and driver takestime and congestion in block section are the minimum affect.

1.2 Free Home Signal is a big safety risk, as totally dependent upon human being, chances of not puttingback free Home signals and trains’ coming over occupied lines are always there.

1.3 Free Home signal not workable if automatic or IBS section on any of the side of the station. Inci-dences of trains coming on ‘A’ marker from auto signal in rear of Home and then by seeing YellowAspect of free Home Signal, coming over occupied lines have taken place on NCR. Similar can be thecase when train is coming on after passing IBS at ON.

1.4 Confusion to loco pilots as Routing Homes Signals if there, are suspended.1.5 Points remain clamped for long time and trains occupying track leave very little time for working on

points during NI working therefore lot of time is wasted.1.6 More requirement of manpower of all agencies involved in NI working.

2.0 How have we overcome this complexity of non-interlocking working and simplify it?In the simplified working being followed on NCR, actually there is no Non-Interlocking working. Switchover

from old system to new system and commissioning is done under a ‘Commissioning Block’. In a yard, involvingremodeling including removal & addition of lines, cut & connection of lines and conversion of rod operatedCLS to motor points for EI, here it is how we go. First step is identifying the activities considering operationalflexibility & need for the phases, which can be done as-

2.1 Preparatory Work –(i). This is the stage in which none of the gears or lines or facilities are suspended and only preparatory

work like insertion of glued joints, changing/replacing of sleepers for point machine fixing & trackcircuits are done under blocks/disconnection of small duration.

(ii). Activities such as laying of new yard lines without disturbing working lines or even dismantling oflines not being used frequently are done to provide new lines & points & crossings. In the Diagram ‘1’in recently done work at Aligarh Junction new points were laid in Pre NI activities D-28 to D-38 anddismantling work to provide connection was done little later at D-11 stage so that facilities were cur-tailed for minimum period

(iii). Signal, Points, Track circuit coming on new line/yard which can be charged directly from EI/PI roomare planned in this phase.

Complexity of Non-Interlocking SimplifiedShri Manmohan Garhwal, CSTE/NCR

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2.2 Pre Block/Pre commissioning Work-This is the stage which starts affecting working gears as well asoperation by partial suspension of some of the facilities and therefore these activities are identifiedand planned to be done after all preparatory works are completed, but before commissioning i.e. ‘D’Day. Type of works which are done during Pre-Block/Pre commissioning phase are-

2.2.1 Track Circuit:-i. Continuous track circuits such as berthing or even point & crossing in which changing of boundaries of

track circuits does no effect existing signaling systems, relocation of Glued Joints and charging ofexisting track circuit at shifted Feed end/Relay End/Jumper end is done.

ii. New Track circuits Feed & Relay end equipments, TLJBs and TLJB to Rail Track lead connection forexisting track circuits are charged from new location, replacing old equipments and track lead connec-tions. TPRs are picked up in New EI room. To pick up TPRs in existing relay Room for working ofpresent gears two ways are followed depending up on availability of cable. In one of the method patchcable is laid between Old & New TR locations or New to old relay Room and TPRS in existing RelayRoom and New Relay room are picked up in parallel. In the second method TPRs are picked in NewRelay Room for existing track circuits and QSPA1 relays spare contacts are used to pick up existingTPRs by providing Patch cable between old to New Relay Room. On the day of commissioning cablegoing to existing Relay room is disconnected either in new location or New Relay Room as the casemay be. It not only simplifies NI/Block working, but also reduces work as well stress on staff forchanging of New Track circuits equipments and connections during NI.

iii. Bifurcation or combining of track circuits for New EI for continuous portion in sequence, if involved isalso done by above method by simply picking up existing TPRs through in series of two bifurcatedtrack circuits or in parallel for combined track circuits.

2.2.2. Signals New Signals which are one to one replacing existing signals at the same location are charged from new EI,

tested by clearing signals for each Aspect including sub-sidiary signals and correspondence of ECR checked innew relay room. After charging and testing of New Signals, New cable towards New EI Room is disconnectedeither at new location of signal or New Relay Rooms and patch cable between old to New location or RelayRoom is used for working of New Charged Signal from old Relay Room, and existing signal number plate ishanged over New Signal number plate. Thus the only work left during NI or Block is to remove existing numberplate. Time saved during NI/Block is in:-

i. Charging of New signal, doing correspondence test during NI,ii. Visualize when single person on Panel and in Relay Room has to give multiple testing for various teams

working in yard, so this time is greatly reduced.iii. Removal of cross from new signals as it will not be there with this present system of NI working.iv. Dis-mentalling or turning off side old signals & providing cross on old Signals, and removing from

New One.v. Confusion to drivers is also eliminated as they become accustom to new Signals.vi. No need of issuing Caution Order for existing signals by SSE in-charge to observe New Signals and

hence his misery is also reduced on NI Day.vii. Similar method is adopted for signals at New shifted location along-with Track circuit charging and

proving it in existing circuitry also.2.2.3 Points-

i. This is one of the important and critical activity which has to be planned jointly with operating officials,when temporary suspension of some lines to do signaling and Engineering work is required. As itreduces operational facilities, therefore are taken later after completion of Pre-NI activities. In theDiagram-2 insertion of points by removing goods lines was done during D-3 to D-5. The movementsover these newly laid points & lines are permitted after commissioning therefore no additional precau-tions are required except existing rodding of rod operated points & supply is disconnection from cabin.,unless connection to running lines is done.

ii. New crossovers on running lines like emergency crossovers and between one line to other are also doneas Pre-NI activities but insertion of any of the crossover in Interlocked area without detections putsspeeds restriction of 15 KMPH in either direction. In diagram 1&2 such points were inserted during D-

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1 to D-15. Lead between two such points was about 3 km in case of Aligarh, and it caused heavydetention of 50 minutes to 1 Hr. in each direction. To reduce detention Detection contacts of pointmachine provided on newly laid point were proved in series with adjacent existing Point Detectionbesides keeping point clamped and 110V operating fuse of New Point Machine removed. This hasrelaxed speed restriction of 15 kmph and only as per Engineering requirement was put.

iii. Conversion of mechanical point to electrical and refitting of old fittings after testing of new one bothmanually and from panel are also done in Pre-NI as it affects working gear & cause failures

2.3 NI/Commissioning Activities:- On NI day the all the gears are brought in to new EI and the activitiesdone are:-

i. Removal of mechanical fittings/old point machine & fitting of New point machine and ground connec-tions of the points identified to be done on NI day.

ii. Testing, Oiling, Greasing and Adjustment of all point done during NI, Pre-NI & Preparatory work iscarried out for proper setting, Detection adjustment as per SEM, correspondence of site position withPanel and Checking of Crank Handle Interlocking & fixing of proper Wards if not done earlier.

iii. Charging of left-over track circuits and making through of Track circuits charged in Pre- NI and dis-connection of connection to old Relay Room Side.

iv. Connection of New signals to New EI Room and disconnection to old relay Room side and Removal ofold number plates.

v. Testing of all signals for proper clearance and Aspect Control check from Panel by clearing routes andchecking of correspondence with site.

vi. Giving the indications of Points/crossovers which are planned in Post NI activities.vii. Finally commissioning of the new system and giving disconnection of gears which are to be under-

taken in Post- NI.

2.4. Post commissioning work after commissioning of the station:-i. New additional crossovers, new sidings, extension of existing siding, new PF lines and goods yard lines

are undertaken. Day wise activities are charted in order of operational priority and feasibility of execu-tion and are named as D+1, D+2 and so on.

ii. Aligarh Yard Remodeling involved cut & connection of UP & Dn Main Line at both the ends of station,requiring longer blocks of 8 to 9 hrs of each line therefore it was not feasible to take continuous blockon both lines and one day gap required after first cut & connect to consolidate track. To accommodatethis, for two days mixed working was continued i.e. on 1st and 2nd Day of commissioning, Up line wasworking from EI, Down line from Mechanical cabins and there was a Mechanical lifting barrier whichwas converted to ELB, on ‘D’ Day to ensure safety, Gate Boom Lock Lever circuit Controller Band wasproved in series with XCR to clear signals for UP or Down.

iii. Gradually left over points either new or coming over after removal of existing points are laid and linewise signals are given after carrying out correspondence test for each Route. In Diagram 1 & 2 it can beseen that at Aligarh Down loop was planned on D+9. Tundla end involved removal of points and theninsertion of New Points, which were done from D+2 to D+9. Similarly at Delhi end activities wereplanned spanning from D+3 to D+9 and in D+3 new PF lines on UP side were given.

iv. Work involved during NI Block are different and depend upon lines involved in yard Remodeling. Incase of Agra, where Up & Down Main lines and PF lines were also involved in Yard Remodelingrequiring insertion of 69 new points and charging of old points. It was not possible to suspend any ofthese points as these were for PF lines, and hence it was not becoming feasible to commission EI on asingle day. Therefore a new system of “One Train One Free Home Signal” was innovated and executedduring NI. At Agra Delhi side is Automatic & Jhansi side IBS, therefore to eliminate incidence ofDriver coming over on occupied lines during NI, this concept was conceived. Minimum Gumties in thearea involved in Yard Remodeling were established and rest of the points were kept clamped. Inter Slotworking between 3 cabins & SM at station were retained by removing all cicuitary except Lever/SlideFrame Bands. Home signal controlling Track circuits were also retained with old equipment for UP &Down Home Signals. In Home Signals clearing circuit only Yellow Aspect was kept and except Lever

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band, controlling track circuit and slot rest of the circuitry was bypassed. With this “One Train One FreeHome Signal” Concept, slot for next train to be received was not possible to come unless previous trainhas cleared station and all slot levers normalized in all cabins and stations. This working continuedsmoothly for 3 days without any detention & unsafe incidence, to switchover 69 old and new points ofMain and PF line alone to new EI and then EI was commissioned on 3rd day evening.

The total yard Remodeling work was completed on D+9 starting from D-45. If this total work is done withconventional method it would have introduced NI work for 55 days with setting up of many Gumties and issueof Authority for all signals because such massive remodeling cannot be done with free Home Signals. Consideringthe density of traffic in Ghaziabad- Kanpur section, impact on safety & punctuality of trains is beyond imagination,if work would not have been done with post NI method. It is the well thought, planned & conceived procedureof Preparatory work, Pre-NI, Commissioning Block & Post NI activities, which simplified complexity of Non-Interlocking working. We can confidently say that it has become a well proven system in last 4 years, becausein the busiest section of NCR massive yard Remodeling with EI have been commissioned at Agra, Cheoki,Naini, Chunar, Hathras, Etawah, Khurja & now Aligarh with the above scheme very smoothly without anytraffic repercussion and most importantly not even a single unsafe incidence has taken place during phaseworks at these stations and that is how complexity of Non-Interlocking has been simplified.

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