Reference material

Control of Approaching , Buffer Stops and Short Overlaps

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This document refers to organisational and positional roles and responsibilities in place prior to 1 July 2013 and may have been superseded by other documents.

Authorised by: Chief Engineer Rail, Asset Standards Authority Published: September 2013

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This document may not be current. Current standards are available for download from the Asset Standards Authority website at www.asa.transport.nsw.gov.au. Rail Corporation New South Wales Engineering Standards and Services Signalling Locked Bag 25 Haymarket NSW 1238 Level 12, 477 Pitt Street Sydney NSW 2000

Signal Engineering

Control of Trains Approaching Catch Points, Buffer Stops and Short Overlaps

Design Guideline

Version 23 March 2006 Approved

Copy No. A coloured number in this space indicates that this document is controlled

This report and the information contained therein have been created solely for a particular purpose and client. This is protected by copyright. You may not reproduce any of it in any form without permission of RailCorp. If you do, you may have to pay damages to RailCorp or you may be prosecuted. Reference material - for information only BY: REVIEWED PRODUC Approved 23 March2006 Version Desi and ShortOverlaps Catch Points,BufferStops Contr gn Guideline ED BY: ED ol of Trains Approaching ol ofTrainsApproaching Chief EngineerSignals Warwick Allison Signal DesignEngineer John Alexander

Reference material - for information only 9 CONCLUS 8 RISK ASS TIMINGMETHODS TO 6 5 INTERMEDIATE 4 CONDITIONAL 3 FUNDAMENTAL 2 REFERE 1 INTRODUC TABLE OFCONTENTS Points,Buffer Approaching Catch Trains Control of SPEEDCONTROLCO 7 . Ueo hr vra n rcinBfe tp...... 12 ...... FrictionBuffer UseofShortOverlapand Stop 7.6 ...... FrictionBuffer Stops 7.5 10 ...... LineSpeedChecking 7.4 10 IntermediateTrainStopsWithReducingSpeeds...... 7.3 7.2 Conditional 9 ...... Mediums CriteriatobeApplied...... 7.1 6 ...... TrainStopOperatingTimes 5.3 6 ...... ITSForCatchpointProtection 5.2 5 ...... ITSforAdditionalSpeed Control 5.1 .. TanSo on...... 11 TrainStopDown...... 7.4.2 10 ...... TrainStopUp 7.4.1 NCES ESSMENT ION ...... 13 ...... 13 ION TION ...... 4 ...... 4 TION ...... 4 ...... 4 CLEARI ST PRINCIPL ...... 13 ...... 13 NFIGURAT CHECK TRAI ...... 5 NG OPS ...... 5 ...... 5 OPS ES...... 4 ES...... 4 tp n hr vras 3Mrh20 Page3of13 23March2006 Overlaps Stops andShort IONS...... 8 IONS...... 8 RailCorp ® N SPEED ...... 6 ...... 6 .8 .. 12

Reference material - for information only Current applications of this are: items, such as bufferstops. This isan existing principle, butwith the The basicprinciple employedisthat the mitigation providedis tomatch the speed of thetrain. 3    2 The methodsareapplicabletoother locations withshortoverlapsandbuffer stops. minimal) operationalconstraints. This paperistodiscuss alternativemethodsofachievingtherequirements,withless(or solution. operationally optimum The results, whilemitigating against high speed derailmentsatcatchpoints, donot provide an . The arrangementsthathavehadbeendesigned usually arerequired tofit inwithexisting train approach speed. conditionally clearedapproach signals and intermediate trainstops have beenused tocontrol As mitigationagainsttrainsrunning pastsignalsatstopandderailingcatchpoints, 1 Points,Buffer Approaching Catch Trains Control of New applicationsare: RiskManagementReport – OverrunProtection at Passenger TrainSidings andTurnbacks CentralTurnbackPlatform Approach ControlofTrains4July 2001 UseofTrain StopstoControlApproachCatch Points RSANovember1999 – Minciv2006 FUNDAMENTAL PRINCIPLES PRINCIPLES FUNDAMENTAL REFERENCES INTRODUCTION Event Mitigation Event Mitigation Train approaches buffers SPAD Intermediate TrainStop(ITS) cleared conditional SPAD after aspect Line SpeedSPAD tp n hr vras 3Mrh20 Page4of13 23March2006 Overlaps Stops andShort Buffer tosuitapproachspeed timing speed Overlap tosuitprevious signal orprevious ITS Short overlaptosuittimingspeed Line speedtrip brakingoverlap application extendedthroughout thesystemtoother RailCorp ® Reference material - for information only prevent thetrainfromrunning outof catchpoints. their train, and while mitigating gross overspeeds, doesnotpresent anideal solution, nor In general,intermediatetrainstops are expectedtocontrol impact onthenaturalwaydrivers treadleforthis purpose reliable asdesired,souseofaCSEED50wheel has beentrialed. forinte arrangements Additionally, DPUtiming . driver isbraking(iereducing speed). Ideallytrainspeedneedstobeconstantoverthetiming while the the timingisperformed It canbedifficultfordriverstojudgespeedcorrectly when up. thetrain andmove torestart thetrainbeingfullyin,whiledriverattempts platform without traindoorsata If driversmisjudgetheirspeed,tripandstop,thentheguardmayopen which isa may thenaccelerate, potential lossof control scenario. results inthe trainthentravellingtooslowlyandafterobservingthestoplower thedriver lower andhenceoften unduly reducespeed in ordertoobservethetrainstopoperate. This finditeasytomaintaintrainspeed whilewaitingforthe trainstoptoDrivers, however,donot train stopadvisory speedboardstoindicatethe speed atwhichtrainsmay pass. current practiceisto provideintermediate that thesearesetat,and to thedriverspeed trainstops.It Additional speedcheckscanbeprovidedbyintermediate isnotreadilyapparent 5.1 5 the timingshouldreflect thehigherspeed. Full useof the available overlapshould bemadeinthatif it is suitable for ahigherspeed,then Sydenham resignallingproject. speed checking should be kept consistent and within therange 160-220mm, forthe adopted condition exists that requires its use.The length ofthetiming trackfor conditional clearing cleared toa fullrunning aspectand thattheconditional clearing isonly inforcewhileverthe thatconditional Consequently itisimportant clearing be usedonasignalthat isusually check ontrain approach speed andhence adequacy oftheoverlap. unfitted trains operate,thereisno arrangementcanmisleaddrivers,andwhere However the saferesult. SPAD hasa Where onlytripfitted trains operate, thetrain stopenforces the stop signal such that any at stop. clearing, and notbeprepared tostop atthesignal. This can resultinthe signal being passed the iftheaspectispermanentlyconditional,thereariskthatdriversmayanticipate However, stop updoes nothavethesamespeedreduction impacttothedriver,asaSTOPindication. tripfittedtrainsoperate,asadisplayedaspectwithtrain wherenon trains. Thisisimportant The benefitsincludebeing abletouseexisting signalaspects, andthe controlappliestoall Conditional Clearing isa usefultool in theapproachcontrol of trainspeed. 4 Points,Buffer Approaching Catch Trains Control of INTERMEDIATE TRAINSTOPS CONDITIONAL CLEARING ITS forAdditionalSpeedControl tp n hr vras 3Mrh20 Page5of13 23March2006 Overlaps Stops andShort RailCorp ® rmediate train stops have proven to be notas rmediate trainstopshaveprovento Reference material - for information only The resultof thisisthatthe trainmayneedto stop andwaitforthetimingtoelapse. speed substantially below thedesign timingspeed inorderto achievethedesignaverage. trains mayenterthetiming point quite legitimatelyata higher speed, and thenhave to reduce The trackcircuitcanonly everassessanaverage other design criteria. Early installationsused existingtrack circuits of tosuit varyinglength,which wereprovided The useoftrack circuits to providetrainspeeds by timingisalways a compromise. 6 Trainstops may take2-3storestore tothenormal position. Other EP - 1s Train stopoperating timeallowances todrivereverseshouldbe: inCBIsystems operating timesareimportant - timeallowances when theoilislessfluid are ofageneralnature.System and haveoperating 0.5s example, hydr stop operatingtimesmayvary.For operating times.Train All calculations mustallowfortrainstopoperatingtimes andsystem 5.3 as beingpast theITS,or theriskis otherwise acceptable. tosuppresstheIt maybepermissible innertrainstopsiftrackcircuits can length provethetrain movements. Additionally, thetrainmaystillbeonatrackcircuitthatholds pointsand thuspreventfollowing being atthe platform. door withoutalldoors an intermediatetrainstop openthe thereisthechance guardmay Millennium trainsbacktrip atquitelow speeds.Ifatrainisbrought toastandprematurelyby way. atthetimeitismostlikelytoberequired,shouldtrainmovewrong removed just and 6car mark. Ifthese trainstops are suppressed for departing trains, this protection is trains are prevented fromachievinganyrunup These ITSareprovide trainstop provided foronedirection may backtriptrainsforthe otherdirection. totraveleitherway, Where intermediatetrainstopsexistinplatforms,andtrains mayneed 5.2 Points,Buffer Approaching Catch Trains Control of TIMING METHODS TO CHECK TRAIN SPEED CHECKTRAINSPEED TIMING METHODSTO Train StopOperatingTimes ITS ForCatchpointProtection d to prevent catchpoint d toprevent runoff intightsituations.Short(4 tp n hr vras 3Mrh20 Page6of13 23March2006 Overlaps Stops andShort RailCorp ® (eg. 1second cycle timeinSSIsystems). by theadditionalITS located just past the 4 aulic typesmaytakelongerincoldweather, speed and henceifthe trackcircuit islong,

and 6car) Reference material - for information only not thensubject tothetiming control. Also atrain may stopontheapproach andtime out, withthe subsequent restartingof thetrain Points,Buffer Approaching Catch Trains Control of tp n hr vras 3Mrh20 Page7of13 23March2006 Overlaps Stops andShort RailCorp ® Reference material - for information only    In undergroundareas,it isusualto:    itisusual to:For example, system design. Additionally a catch point should be used asacontrolforevents beyondtheusual criteriafor below, aspeed thatthe overlap canmitigate. As afundamentalprinciple,thespeed oftheapproaching beat,or trainneedstoproven       The aimsofanyspeedcontrolarrangement shouldbeto: 7.1 7 allowing some adjustmentofthetimereitherlowerorhigher. Timing isusuallysetto5secondswhich isthe withthistechnology. arrangement respectable familiarityandtrust inoperation andis hence seen tobe the optimum gain some trainstopwouldenabledriversto distance prior tothe a shorttiming the useof If reliabilityoftimingis assured, and intermediatetrainstop advisoryspeedboardsprovided, unreliable. in asignificantimpactonthetimingandhencedr reliabilities,If aproblemexistswith DPU timing operation of the system. approach would resultHowever this inabetter train speed profile if the drivercould ‘trust’the this. not beingable slowdowntoachieve toviewthetrainstop dropaheadandhencetheymay required (orclosertothe required)pointtoachieve trainstop operation. This results in drivers short timing Conversely Points,Buffer Approaching Catch Trains Control of Capacceleration attheline speed. UsetheGE52curve Applyaccelerationafter aspeedcheck thishigher andan speed overlap accommodating UsetheGE52Acurveforoverlapbrakingcalculationsaboveground. linespeed of onlytoamaximum Applyoverlaps Notapplyaccelerationafter aspeed check in above groundinstallations Avoidconditionalclearing which Reduce,as far asispractical, reliance observethetrainstop onthedriverhavingto Be reliable Controlthetrainspeedto suittheconditions ahead incidents Preventmajor Notundulyimpactonnormaldriverbehaviour SPEED CONTROLCONFIGURATIONS SPEED Criteria tobeApplied tracksare able tomuch may increasetheincidence of SPAD. tp n hr vras 3Mrh20 Page8of13 23March2006 Overlaps Stops andShort RailCorp ® minimum feasible using a QTD5 relay whilestill feasibleusing a QTD5relay minimum however, a small delayintrainshunthowever, a canresult moreaccurately‘sample’the speed atthe iver judgement would ranktheinstallation iver judgementwould Reference material - for information only For thistobe effective,the trainmustbewellin advanceoftheconditionalsignal so medium caution indication thetrainisapproachingtostep to medium. tocaution,andthuspermitthe sufficiently slowlytopermitasignalaheadclear fromstop travelling beprovedto trainapproachingacautionsignal may In thisarrangement,a into aplatform) andnonontripfitted trains operate, thenaconditional mediumcanbeapplied. Where trainsmayapproachashortoverlap,andit 7.2    Should eventsoccuroutside these Points,Buffer Approaching Catch Trains Control of Conditional mediums wereextensivelyusedontheHarbourBridge 1932–1990.      consideration ofthefollowing criteria:- Conditional Medium’sshouldbedecided onacasebybasisandThe useof include speed arenecessary. wheel detectorslocated 5 seconds travel timeapart(orasuitable trackcircuit)atthe required Such aconditionalmediumwouldrequiretimingstartand finishpoint, andhencetwo D50 this timingpoint, theusual conditional caution clearing wouldapplyatthefollowingsignal. suitable forthistooccur. trainmiss thesignalwouldbe Should the A pointabout100mbefore theindication. that thedrivermayobserve Havingaverylowprobabilitythat previ Havinganoverlaplongerthanaminimum Useofacatch point Operationaladvantages vsriskdisadvantages – Trainaccelerating at or past timing due tostartingfromastation,section, whichmaybe Distancefrom ConditionalMediumsignaltostop signal–riskoftrainaccelerating iftoo far. TrackGradient –rising temptsdrivertoaccelerate – failing grade demands greater Length of Overlap – minimum margin ofsafety LengthofOverlap–minimum mustbemaintained,particularly inthe case gain outweighedbythe additional risk. controlled signal, permanent speedrestriction, etc. braking control overtrain. of flankprotection. Conditional Mediums criteria mitigation isless assured and may beby: tp n hr vras 3Mrh20 Page9of13 23March2006 Overlaps Stops andShort RailCorp ® ous trainwouldstop hardonanoverlappoint. is desired to advance trains (for example trains(for example isdesiredtoadvance is it worth the gainand istheadditional Reference material - for information only The following situations may usealinespeedchecking : greater confidenceforthe driver. than theline speedoverlap) thenthe trainstopwill lowerbefore thetrain reaches it, providing If thetiming isset fora higherspeed, thanthe linespeed (ie theavailableoverlapislonger byspeedboardoraturnoutontheThe linespeed approach. maybeset providing conditionallow speedsignals. insomecircumstances to preferable approaching may be araisedtrainstop,however it The problem withsuchanarrangementhoweveris operation of the trainisbeing confirmed. this isthat no specialsignalaspects needtobedisplayed,norspeedboards,asthenormal Some circumstances mayexistwhereline speed checking canbe employed.The benefit of TrainStopUp 7.4.1 7.4 “Central TurnbackPlatform 23”. whenaccelerationis to beallowedfor(egarrangement tunnel situations)isdescribed in document “UseofTrainStopsto Control ApproachSpeedtoCatchpoints–1999”. The The arrangementsforintermediatetrainstopsinabovegroundsituations isdetailed inthe recommended. isessentialHowever, it forthetiming tobereliable, and henceuse ofDPU’sinnotnow provided andthetrainstop islocated onanotherwise potentially illdefined brakingcurve. overprev This isasignificantimprovement train stopto operate. Consequently thedrivercanproceed ataconstant speedoverthetimingtrackandexpect the intermediate trainstopadvisory ofthetimingpoint. speedboardat the commencement The speed at whichthe intermediatetrainstops aretimedisprovided tothedriver onan further checksusing intermediate trainstopswhen theoverlapisonlysuitable foralow speed. practiceforthetraintothenexperience While notexplicitlystatedintherules,itiscommon proceed at25km/h orless. lower speeds,thedriverisprovidedwithalowspeedindicationthat advisesthedriverto trainstopstoprogressivelychecked usingintermediate When trainspeedisneededtobe 7.3 Points,Buffer Approaching Catch Trains Control of Line Speed Checking Line SpeedChecking Intermediate TrainStopsWithReducingSpeeds tp n hr vras 3Mrh20 Page10of13 23March2006 Overlaps Stops andShort RailCorp ® ious installations wherenospeedadviceis ious that drivers may not particularly like thatdriversmaynotparticularly Reference material - for information only To datethis method hasnotbeenimplemented. monitored andalarmedifexcessive. should also be providedtoensurethatthetime ittakestorestoreoncethedriveisremoved The train stop should be provento cyclefor each train and itsoperationproved. Atimer ensure thelimitsareunderstood. used at higher speeds. The sensitivity ofanyproposedarrangement shouldbe calculated to While 5sec is theminimumtiminglength, accuracy will improve ifalonger distance is for (Note:thismaybehigherthanline speed). ifisrequired tocater speed ensure adequatetimeforthetrainstoptoraise, atthemaximum andthetrainstopneedstobeprovided A suitabledistancebetweenthesecondtimingpoint be thenormaltrainstop arm risesandthetraintrips.Thestopmay at asignal. concept, if the traindoes notmeetthe timingcriteria,the train stop drive isremoved,andthe considered. As analternative,theuseoftrainstopraisinginfront Withthis ofthetrainmaybe TrainStop Down 7.4.2 assurance for thedriver. approach and hencethe tripwould bedownbeforethedriverreachesit,permittinggreater collision with thebuffer stop. This location should bewell past the braking pointfor anormal role is to be abletoreduce atrain travellingat 35km/h(in the example)to15km/hbefore Note the15km/htrainst ahead. In thesecasesthe35km/hrischosenasitabovelinespeed,butsuitableforoverlap Points,Buffer Approaching Catch Trains Control of ops canbe located ash tp n hr vras 3Mrh20 Page11of13 23March2006 Overlaps Stops andShort RailCorp ® ort distance in frontofth e bufferstops astheir Reference material - for information only has beenchecked at25km/h. needs nointermediatetrainstopsprovidingtheapproachspeed This arrangementthen final speed. can beused tomitigate aspeed of 25km/hto 15km/h,withthefrictionbuffer mitigating the red signaland fixedtrainstop.If a 15km/h bufferis located atthe40m location, then the40m beyond thetr below,thereis60m In theexample usedtomitigatetheexcessspeed.buffer maybe Where anoverlapisprovided,butnotsufficient fortheapproaching trainspeed,afriction 7.6 clearly identifiedindesigns. other criteria.Designersshouldensure thatbufferstopspeedanddistancespecifications are These distances include thebufferstopstructurewith manufacturerand vary length,but may 10m 25km/h 33m 15km/h 15m 8km/h Typical distances are: required space behinda friction buffer stopforthe impact speed mustbeprovided. areavailable.The practical application bufferstops with costandspace.However,25km/h Typically 8km/hfriction buffer aresuitablefor sidings,with 15km/h beingclose to themost approach trainspeed.track isprovidedandthebufferstopdesignmustbeintegratedwith The useoffrictionbuffer stopscanassist inmitigation oflowspeed overrun.Ashortoverrun 7.5 Points,Buffer Approaching Catch Trains Control of Use ofShortOverlap andFrictionBuffer Stop Friction Buffer Stops tp n hr vras 3Mrh20 Page12of13 23March2006 Overlaps Stops andShort RailCorp ® ain stopping point, which is marked by a fixed by afixed ain stopping point,whichismarked Reference material - for information only

and overrunmeasurestosuitoperational arrangements. Signal designers should track aimtoinfluence designers in theprovisionofsuitable overlaps The concept ofspeedproving fortheavailableoverlapremains. speed controlled signals andintermediatetrainstops. This paperistoshowdifferent techniquesthatcan beemployedtoimprovedriverresponse on 9 toproperlyassessthemay beneeded specific situation For scenariosnotcovered bythisdocument and theriskassessment,a newriskassessment Services PtyLtd,December2005. entitled “OverrunProtectionatEpping andChatswoodTurnbacks”byManagement Minciv Risk Management Report are supportedbya inthisdocument The principlesandmethods 8 Points,Buffer Approaching Catch Trains Control of CONCLUSION CONCLUSION RISK ASSESSMENT tp n hr vras 3Mrh20 Page13of 23March2006 Overlaps Stops andShort RailCorp ® .