l8 rail signalling
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Railway signalling
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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
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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
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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
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.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-
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.lock signalling/
• 0istory
• 1ntering & lea'ing a manually%
controlled #lock• 2ermissi'e #lock
• "utomatic #lock
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.lock signalling/
• Method to determine #lock status
– Track circuit
– "+le counters
• Types o #lock
– 3i+ed #lock
– Mo'ing #lock
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"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-
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"spects and indications
• "spect , the 'isual appearance o thesignal
• Indication , the meaning
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!ignalling/
• 3i+ed signals
• Route signalling
•
!peed signalling• "pproach release
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!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
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!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-
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!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
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!ignal mounting
• !ignal mounting
• 2ost mounting
•
:antry mounting• :round mounting
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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!
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6ontrol & operations o
signals--• ;e'ers were placed in special
#uilding known as
– !ignal #o+ (UK
– Interlocking tower (U!
• Modern system , computer
controlled
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!aety system
• 6a# signalling
• Interlocking
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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.
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A British semaphore signal on the
$ormer Southern %egion o$ British
%ailways
&etwor %ail two-aspect
colour light railway signal
set at danger
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'wo-head color position signal
on (S)' mainline at Sa*age!
Maryland. 'he le$t head displays
+Stop+! the right head! +(lear+.