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SIGNALING IN RAILWAYS

Digajerla Suresh

14CM43F

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Elements of a Signaling Yard

• Signals• Track Circuits• Points

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CLASSIFICATION OF SIGNALS

SIGNALS

FUNCTION PURPOSELOCATION OPERATION

STOP

WARNER

DISC

COLORED

OUTER

HOME

STARTER

ADVANCE

ROUTING

REPEATER

CALL ON

HAND

FIXED

DETONATING

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STOP SIGNAL

The length and width of arm vary from

120-167 cm and 23-35 cm respectively

The outer end of the arm is about 2.45 cm

Broader than that of the hinged end

It is placed on the left hand side of the direction of movement of train

The side of the arm facing the driver is painted red with white band near the end

The other side is painted white with black bands

7.67 m

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WARNER SIGNAL

These signals are similar to stop signals with the exception that at their free end V notch is cut to distinguish it from stop signals

Signals placed ahead of the stop signals to warn the driver before entering the station

Warner signals are placed generally at about 540 m away from the stop signals

SIGNAL INDICATIONS

Inclined Position: Track is clear and driver can proceed with confidence

Horizontal Position: Deriver can take his train upto Stop signal cautiously

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SEMAPHORE AND WARNER SIGNAL

Semaphore and Warner Signals can be placed on same the pole. Semaphore is placed on top and the Warner at about 2 m below itSIGNAL INDICATIONS

Both in Horizontal Position: Neither approaching section nor next block is clear

When Semaphore is inclined and Warner Horizontal proceed with precaution i.e. section up to station is clear but not the block beyond.Both in Inclined Position:Track is clear and proceed with confidence

SEMAPHORE

WARNER

SEMAPHORE

Operation Time Position Of Arm Position Of Signal Indication Given

Horizontal Arm ON Stop

Inclined At 60o or 45o OFF Proceed

Red Light ON Stop

Green Light OFF Proceed

Day Time

Night Time

STOP SIGNAL

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DISC SIGNAL

These are shunting signals which are used for low speedmovements during shunting operations. They consist of circular discs with red bands on white background

SIGNAL INDICATIONS When Red band is Horizontal: Stop

When Red band is Inclined: Proceed

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RAILWAY INTERLOCKING

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ASS

SSHS

OS

OHS

SIGNALS ACCORDING TO LOCATION

INTERLOCKING STANDARDS

STANDARD-I Applicable for station for train speeds upto 50 kmph

STANDARD-II Applicable for station for train speeds upto 75 kmph

STANDARD-III Applicable for station for unrestrictedspeeds

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ROUTING SIGNAL

When many branch lines diverge in different directions from the main line, it is very difficult to provide individual signal for each line at the divergent point.In such situations various signals for main line and branch lines are fixed on the same vertical post. These signals are called routing signal. Generally signal for main line is kept higher than those for branch lines

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Track Circuits

• Track Circuits are devices that convey the presence of a train on a specified length of a track

• There are many types of track Circuits available as follows:1. DC Track Circuits2. High Frequency Track Circuits (HFTC)3. Audio Frequency Track Circuits (AFTC)4. Axle Counters ( Digital & Analog )

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Device Electronics

Tracks

Relay Contacts Available for other Higher Level Devices such as SSIs

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SPACE INTERVAL METHOD

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OVERLAP SIGNAL

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TRACK CIRCUITED OVERLAP

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TRACK CIRCUITED OVERLAPS

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ABSOULTE BLOCK

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METRO TRACK CIRUIT

AUTOMATIC SIGNAL SYSTEM:

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Points • Points also referred to as switches are mechanical

devices in the railway to change the path that trains may take through a junction. The switch positions are called normal and reverse• These mechanical switches can be manually or

Electrically Operated to Change From Normal to Reverse or Vice-Versa

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REFERENCES

• Indian Railways Year Book 2002-2003• http://www.railway-technical.com/sigtxt2.shtml• http://

www.eng.ox.ac.uk/InvensysUTC/other%20research/railway-points-machine

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THANK YOU