Indian Railway Signals & Systems

This presentation is all about various signals and systems adopted in the Indian Railway

1. SIGNALS ON
RAILWAY
Prepared By:
Arbaz Kazi
Asst. Professor
VCET, Vasai (W)

2. •Railwaysignallingisasystemusedtocontrol
railwaytrafficsafely,essentiallytopreventtrains
fromcolliding
•Signallingconsistsofthesystems,deviceandmeans
bywhichtrainsareoperatedefficientlyandtracksare
usedtomaximumextent,maintainingthesafetyofthe
passengers,thestaffandtherollingstock.
•Itincludestheuseandworkingofsignals,points,
blockinstrumentsandotherequipment's.
SIGNALS IN RAILWAY

4. Toprovidefacilitiesfortheefficientmovementoftrains.
Toensuresafetybetweentwoormoretrainswhichcrossor
approacheachother'spath.
Toprovidefacilitiesforthemaximumutilityofthetrack.
Toprovidefacilitiesforsafeandefficientshunting
operations.
Toguidethetrainsmovementduringmaintenanceandthe
repairsofthetrack.
Tosafeguardthetrainsatconvergingjunctionsandgive
directionalindicationsofdivergingjunctions.
Objects of Signalling

5. Types of
Signals
According to
Function
Stop Signals
Warner
Signals
Disc Signals
Coloured
Light Signals
According to
Location
Reception
Signals
Outer Signal
Home Signal
Departure
Signals
Starter
Advance
Starter
Special
Signals
TYPES OF SIGNALS

6. ➢Oneoftheearliestformsoffixedrailwaysignalis
thesemaphore.
➢Thesesignalsdisplaytheirdifferentindicationsto
traindriversbychangingtheangleofinclinationofa
pivoted'arm’
➢Thestoppositionisthenormalpositionanditissaid
tobeONposition
➢Thearmcanbeloweredatanangleof40°to60°with
horizontalandissaidtobeOFFposition
Stop Signals or Semaphore Type Signals

7. http://www.readorrefer.in/media/extra/sP3tplo.jpg
https://goo.gl/XEddaF
Stop Signals or Semaphore Type Signals

8. •Thewarnersignalissimilartosemaphoresignalin
shapeexceptav-notchatfreeend,i.e.Themovablearm
isfishtailedasshown.
•Thewhitebandisalsoofv–shape
•Thewarnersignalisplacedonthesamepostofthe
semaphoresignal1.8to2.1mbelowthesemaphore
signal.
•Thewarnersignalispaintedyellowandexhibitsyellow
orambercolouratnightinsteadofredcolour
Warner Signals

9. http://www.readorrefer.in/media/extra/B4WgETa.jpg
Warner Signals

10. ❖Thesesignalsareusedforshuntingoperationsinstation
yards
❖Theyareoftheshapeofacirculardiscwitharedbandona
whitebackground
❖Thedisccanrevolveinaverticalplanebypullingthelever
byhand.
❖Twoholesareprovided,oneforredlampandtheotherfor
thegreenlamp.
❖Whentheredbandishorizontalorshowsredlightatnight
itindicates―STOP
❖Whentheredbandisinclinedat45degreeorshowngreen
lightatnightindicates―PROCEED
SHUNTING SIGNALS

11. SHUNTING SIGNALS
http://www.readorrefer.in/media/extra/Y7wo9Ri.jpg

12. Semaphoresignalsarebeingreplacedbyhigh
intensitybeamcolourlightsignalsbothduringday
andnight
Incaseofcolourlightsignals,thenormalpositionis
toindicate―PROCEED (i.e.,showsgreenlight)
Whenthesectionisblocked,itautomatically
indicates―STOPor―DANGER (i.e.,showsred
light)
InIndiathesesignalsareusedonurbanandsub-
urbansectionswithheavytraffic
Colour Light Signals

13. http://www.irfca.org/faq/images/macl.gif
Colour Light Signals

14. Signal Box Layout
https://goo.gl/LvKRQh

15. ➢This is the first stop signal which indicates the entry of the
train from block to the station
➢It should be placed at an adequate distance (0.54km for BG
and 0.4 km for MG)
➢It has one arm but may have a warner signal on the same
post nearly 2m below it.
➢In the Stop position the driver must bring his train to a stop
at a distance of about 90m before the outer signal and then
proceed to the home signal with caution
➢If it is in the Proceed position then the driver can take the
train at speed, assuming that home signal is also in the
proceed position.
Outer Signal

16. •Duetoitslocationatthedoorofstation,itistermedas
Homesignal.
•Thehomesignalhasbracketedarmstoindicatewhich
lineistobeused.
•Thefunctionofhomesignalistoprotectthesidings
alreadyoccupied.
•Itislocatedatnotmorethan180mfromthestartof
pointsofswitches.
•Homesignalscarryasmanyarmsasthenumberof
diverginglines.
Home Signal

17. ❖Itmarksthelimituptowhichtrainsstoppingata
stationshouldcometoastand
❖Thestarteristhelaststopsignalatastation
❖Itcontrolsthemovementsofthetrainswhenthey
departfromthestations.
❖Notraincanleavethestationunlessthestarter
signalshowsthe―PROCEED position(i.e.,inclined
position)
Starter Signal

18. Besidesthestartersignalforeachofthestation
linesfromwhichtrainsstarts,anadvance
startermayalsobeprovided.
Theadvancestarterbecomesthelaststop
signalatthestationswhereveritisprovided.
Itisanindicationforthetrainhavingleftthe
station
Advance Starter Signal

19. Whenatrainpassesthroughastationwithoutstopping,the
drivercomesacrossthefivesignalsinthissequenceWARNER,
OUTER,HOME,STARTERandADVANCESTARTER.
Whenthedriversvisionisobstructedbyanoverbridgebetween
thesignals,asignalisprovidedwithaduplicatearmofsmaller
sizeatasuitablepositionwhichrepeatstheindicationofsignal
head.ItisthereforetermedasRepeatersignal.
Thissignalislinkedwiththemainsignalandtherefore,when
theleverispulledbothsignalsareloweredsimultaneously.
Alsocalledas―co-actingsignal
Special Signal
Repeater Signal

20. https://goo.gl/JYdXsh

21. ❖Whenvarioussignalsformainandbranchlinesare
fixedonthesameverticalpost,theyareknownas
routingsignals.
❖Generallythesignalforthemainlineiskeptathigher
levelthanthatforbranchline.
Routing Signal

22. ➢Theseconsistofsmallandshortarmsfixedonthesame
postbelowmainsignals
➢Acalling-onsignalpermitsatraintoproceedcautiously
afterthetrainhasbeenbroughttoahaltbythemain
signal
➢Thissignalsarehelpfulwhenrepairworksaregoingon
Calling -On Signal

23. •Variousotherdevicesareusedforindicatingsignals.
Signalsaremeantforgoodssidingsaredistinguished
byprovidingringsorwritingcapitalletterSetc.,
•Twocrossedbarsareputuponthesignalwhichis
underrepairanditisplacedinONposition.
Miscellaneous Signal

24. Itisquiteessentialthatmovementsoftrainson
particulartracksshouldbesafeandforthis
purposevariousmethodsarefoundout
(i)Followingtrainssystem
(ii)Absoluteblocksystem
(iii)Automaticsignalling
(iv)Pilotguardsystem
Control of Movement of Trains

25. •Usedincaseofemergenciessuchasfailureof
telegraphandtelephonesystems.
•Inthismethod,afixedintervaloftimeis
maintainedbetweenthedepartureofonetrain
andthedepartureofthenexttrainalongthe
sametime.
•Thisfixedintervalisworkedoutinsuchaway
thatsufficientdistanceorheadwayinmaintained
betweenthetailofthefirsttrainandtheheadof
thenextfollowingtrain.
Following Trains Systems

26. Theprincipleoftheabsoluteblocksystemofrailwaysignallingisto
ensurethesafeoperationofarailwaybyallowingonlyonetraintooccupy
adefinedsectionoftrackatatime
•Insteadofafixedintervaloftimebetweensuccessivetrains,avarying
intervalmaybekeptdependingonthetime,actuallytakenby
particulartrains.
•Itisaspaceintervalsystemratherthanafixedintervalsystem.
•Intheabsoluteblocksystemthelineisassumedtobeblockeduntilthe
factthatthelineisclearisestablishedbysomesuitableinformation
conveyedbyblockinstruments
•Theelectrictelegraphprovidedtheabilityforsignalmento
communicatewitheachotherandprovidedthebasisfortheabsolute
blocksystem
Absolute Block Systems

27. Absolute Block system

28. Inordertoavoidaccidents,automaticsignallinghas
beenfoundout.Inthissignalsareoperatedbytrains
themselves.
Anelectriccurrentisconveyedthroughthetrackwhena
trainoccupiesthatparticulartrackandthiscurrentputs
thesignalatdangerpositionuntilthetrainhasgonefar
aheadsoastorequirenofurtherprotection
Automatic Signalling

29. Centralizedtrafficcontrol(CTC)isaformofrailway
signallingthatoriginatedinNorthAmerica
Thesystemconsistsofacentralizedtraindispatcher'soffice
thatcontrolsrailroadswitchesintheCTCterritoryandthe
signalsthatrailroadengineersmustobeyinordertokeep
thetrafficmovingsafelyandsmoothlyacrosstherailroad.
CTCsystemsareconsideredsufficientauthoritytorun
trainsbasedstrictlyonsignalindications.Thisisbecause
CTCsignalsdefaultto'Stop'andrequireahuman
dispatcherto'Clear'them.
Centralized Traffic Control

30. Centralized Traffic Control

31. Inrailwaysignalling,aninterlockingisanarrangementof
signalapparatusthatpreventsconflictingmovements
throughanarrangementoftrackssuchasjunctionsor
crossings
✓Anarrangementofsignalsandsignalappliancesso
interconnectedthattheirmovementsmustsucceedeach
otherinpropersequence".
✓Ingeneraltermsaninterlockingisalocationwhereplain
trackendsandtrackworkwithpointsandcrossings
complicatetrainmovements.Theseareasarelikelytobe:-
oJunctionswheretwoormoremainlinesmeet.
oComplexyardsorsidingsareencountered.Thesemaybeat
largertownsordepotfacilities.
✓Aninterlockingprovidesforcomplextrainmovements
andshuntingoftrains.
✓Itprovidesfortheprotectionofmultipletrainmovements
withinalocalisedarea.
Interlocking of Signals

32. ✓Notpossibletolowerthesignalsfortheadmissionsoftrainsfrom
oppositedirectionorconvergingdirectionsatthesametimetothe
sameline
✓Notpossibletolowerasignalforanyapproachingtrainuntilthe
correctpoints
✓Notpossibleforloosewagonsfromanypartoftheyardtoobstructthe
linewhichissetforincomingtrainafterloweringthesignal
✓Whenthesignalislowered,itshouldnotbepossibletodisconnectany
pointorreverseunlockthepointsuntilthetrainhaspassedand
signalshavebeenraisedtoits―ONposition.
✓Notpossibletolowerwarnersignalunlesshomeandstartingsignals
haveloweredinadvance
Principles of Interlocking

33. ➢Thesignalsandpointsareoperatedbymeansoflevers.
➢Leversarelocatedatgroundlevelorplatformlevelor
inanelevatedstructurecalledsignalboxorsignal
cabin
➢Interlockingisdonebygroupingleversatonepoint
➢Theleversarepaintedforeasyidentification
➢Therearethreemethodsofinterlocking
(i)Tappetsandlocksystem
(ii)Keysystem
(iii)Routerelaysystem.
Methods of Interlocking

34. Tappets and lock system

35. Route Relay system