l8 rail signalling

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Railway signalling



Railway signalling

• Is a system used on railways tocontrol trafc saely

•

The set o rules & physicalequipment used in control is knownas

– Method o working (UK

– Method o operation (U!

– !aeworking ("us



Timeta#le operation

• $peration according to timeta#le

• Trains can only operate in pre%arranged time periods

• isad'antages o timeta#le – o positi'e con)rmation that the track is

ahead is clear

– In*e+i#ility – Inefcient



Timeta#le & train order

• Telegraph , )rst system a'aila#lewher msg could #e transmitted asterthan trains-

• "llow the dissemination o alterationsto time ta#le known as train order



.lock signalling

• .ritish lower%quadrant semaphorehome signal with calling%on arm(permissi'e #elow-

• Railway lines are di'ided intosections known as #locks & only onetrain is normally allowed in each

#lock at one time-



.lock signalling/

• 0istory

• 1ntering & lea'ing a manually%

controlled #lock• 2ermissi'e #lock

• "utomatic #lock



.lock signalling/

• Method to determine #lock status

– Track circuit

– "+le counters

• Types o #lock

– 3i+ed #lock

– Mo'ing #lock



"pplication & positioning osignals/-

• !ignals can #e placed4

– at the start o a section o track (with#lock signalling-

– on the approach to points5switches-

– in ad'ance o other signals-

– on the approach to le'el crossing-

– ahead o platorms or other places thattrains are likely to #e stopped-

– at train order stations-



"spects and indications

• "spect , the 'isual appearance o thesignal

• Indication , the meaning



!ignalling/

• 3i+ed signals

• Route signalling

•

!peed signalling• "pproach release



!ignal orms

• Mechanical signal

–!emaphore signals

• 6onsists 7 parts 4 a #lade or 'ane orarm which pi'ots at di8erent angles& a spectacle holding colored lenseswhich mo'e in ront o a lamp in

order to pro'ide indications at night• 6ontrolled through mechanical

linkages



!ignal orms/-

• 6olor light signals – 1lectric light #ul# produce color light

signals which were #right enough to #e

seen during daylight- – 7 orms

• Multi%unit type with separate lights & lensesor each color

• !earchlight signals , a single incandescentlight #ul# is used to each head & relay isused to position a colored spectacle in ronto the lamp-



!ignal orms/-

• 2osition light signal – $ne where the position o the light9 rather

than their color determine the meaning-

– "spects consist

• 2attern o illuminated lights

• 6om#ination o color & position signalsystem – Use a main signal head which ha'e pairs o

colored lights-

– "llowed reading the aspect correctly i oneo the #ul#s ailed



!ignal mounting

• !ignal mounting

• 2ost mounting

•

:antry mounting• :round mounting



6ontrol & operations osignals

• Manually operated to display simplestop5 proceed directions

•

istant signal %ga'e the dri'er5 engineerwarning that he was approaching asignal at which he would ha'e to stop

• 6ontrolled #y le'ers that grouped

together & connected to the signal #ywire ca#les or pipes supported on rollers(U!



6ontrol & operations o

signals--• ;e'ers were placed in special

#uilding known as

– !ignal #o+ (UK

– Interlocking tower (U!

• Modern system , computer

controlled



!aety system

• 6a# signalling

• Interlocking



A British lower-quadrant

semaphore home signal with

calling-on arm below.

A Finnish distant signal at the

western approach to Muhos

station is displaying Expect Stop.

In the bacground! express train

"# is pulling away $rom the

station.



A British semaphore signal on the

$ormer Southern %egion o$ British

%ailways

&etwor %ail two-aspect

colour light railway signal

set at danger



'wo-head color position signal

on (S)' mainline at Sa*age!

Maryland. 'he le$t head displays

+Stop+! the right head! +(lear+.

l8 rail signalling

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