RailroadSignaling101

AnOverviewandHistory

DavidA.Ellis Division12,MCR,NMRA

RailroadSignaling101

•  Overviewofsignaling,nota“howto”•  Focusonprototypesratherthanmodeling•  Somebasicterms•  Whyrailroadsdevelopedsignalingsystems•  Chronologicalapproach•  Basicoverviewwithoutallthenuances•  Bibliographyhassourceswithmoredetails

SignalTerms

•  Aspect:Whatitlookslike--thecolororthepositionofthebladeorrowoflights

•  Name:Thewordsusedwhentalkingaboutit

•  Indication:Whatshouldbedonewhenitisseen

WhyDifferentSignalSystems?

•  Purpose–Safetyandincreasetraffic•  Era–Othertechnology:telegraph,radio,etc.•  Prototype–Whattherealrailroaddid•  DispatchingSystem–Signalsystemsmatchwithcorrespondingdispatchingsystem

HandandFlagSignals

•  PRRrulebookIllustrationfrom:

•  TonyKoesterhasadaptationsformodelers

WhistleSignalsRule 14 Engine Whistle Signals

A short sound is designated by “0” and a long sound by a “- -”

0 Apply brakes -- Stop

---- Release brakes – Proceed Forward

000 Release Brakes – Reverse Back

----0-- Grade Crossing (last long extended)

Ring Bell when public contact possible and on bridges!

TrainOrderSignals

MikeHauk’sLayout,PhotobyMikeHaukwithpermission

TrainOrderSignals

•  UsedwithT&TOdispatching.

•  Typicalsignalwasupper-quadrantsemaphore

•  Signalswhetherordersormessagesforpick-up.

ManualBlockSignals

•  Earlysignalingsystem•  Mainlineisdividedintosectionsorblocks•  Operatorkeepingtrackoftrainsenteringandleavingtheblockstationedateachend

•  Operatorabletocommunicatewithotheroperatorsand/ordispatcher

•  Eachblockstationequippedwithasignal

ManualBlockSignals

•  Signalaspectssimilartotrainordersignalsorred,yellow,andgreen

•  Theredaspectisastopsignal;theindicationistostopbecausetheblockisoccupied

•  Theyellowaspectisaproceedatatrestrictedspeedsignal;theindicationistotravelslowenoughtobepreparedtostopshortofaprecedingtrain

•  Thegreenaspectsignalstoproceed,theblockisclear

1956NewYorkCentralRulesoftheOperatingDepartmenthttps://nycshs.org/about-n-y-c/nycs-signal-rules/

AutomaticBlockSystem-ABS•  InsimpleABS,alowvoltagetrackcircuitdetermineswhetherablockisoccupied.

•  ABSpermittedshorterblocks,increasinglinecapacity,andrequiredfewernumbersofpersonnel,reducingcosts.

•  ABSisapermissivesystem,aprotectiveoverlay,allowingtrainstofolloweachotherinasafemanner.

•  AtypicalapplicationisusingABSwithadoubletrackmainlinewithonedirectionoftraveloneachtrack.

AutomaticBlockSignals--ABS•  Threeblocks,traininthethirdblock,

travelingtotheright

•  Redsignal,obstructioninnextblock•  Yellowsignal,obstructedblockahead•  Greensignal,noobstructionisexpected.•  Whenthetrainmovestothenextblock,

redchangestoyellowandyellowtogreen.

Train

AbsolutePermissiveBlock-APB

•  ABSwithextrasafetyfeatures•  Singletrackmainlines•  Preventopposingtrainsfrom“meeting”•  Absolutesignalprotectionbetweenpassingsidings

TowerandTracksatDevalInterlockingC&NWBySlambo-Ownwork,CCBY-SA2.5,https://commons.wikimedia.org/w/index.php?curid=433758

InterlockingPlant

• Definition:Anarrangementofsignalandturnoutcontrolsinterconnectedtopreventconflictingmovementsthroughtracksatcrossings,junctions,andcrossovers.Thesemaybeoperatedmanually,automatically,orbyremotecontrol.

InterlockingSignals

•  Name:ApproachSignal

•  Aspect:Typicallyasearchlightsignalwithayellowlight.

•  Indication:Proceedatrestrictedspeedpreparedtostopatnextsignal

•  Name:HomeSignal•  Aspect:Redorgreen•  Indication:Absolute,red=stopbeforesignalgreen=freetoproceedatslowspeedthroughtheinterlocking

CentralizedTrafficControl

EdCronin’sB&LELayout

CentralizedTrafficControl-CTC

•  TrafficControlSystem•  Trainsrunonsignalindicationonly•  CTCPanels•  Interlockings,ABS,andtrafficlockingcombined

•  Singledispatcheroverlargesectionofrailroad•  Dispatchercontrolsandmonitors

Signaling 1.01 An Overview of Prototype-Model Signal Systems!

By Michael J. Burgett Division Engineer of Signals Chicago and Michigan Division Canadian National Railway

EduTRAIN™

PositiveTrainControlandSignals?

Bibliography•  ABS,InterlockingandTCS/CTCbasicshttp://www.lundsten.dk/us_signaling/signalbasics/•  JohnArmstrong’s1957Trainsmagazinearticlesonsignaling

http://nttmuseum.org/kids/signals.pdf•  “RailroadSignals:WhatTheyDo,WhatTheyMean,”Trains

Magazine,FrankW.Bryan,RobertSMcGonigal,May1,2006,trn.trains.com/railroads/abcs-of-railroading/2006/05/railroad-signals•  RealisticModelRailroadOperation2ndEdition,KalmbachBooks,

TonyKoester,2013•  RailroadSignalsoftheU.S.:OtherFormsofSignalingwww.railroadsignals.us/other/hand/index.htm•  WikipediaarticleonABS,https://en.wikipedia.org/wiki/Automatic_block_signaling