signalling in railways

Signalling : Signalling consists of the systems,

devices and means by which trains are operated efficiently and tracks are used to maximum extent, maintaining the safety of the passengers, the staff

and the rolling stock.

NEED OF SIGNALLING

• To provide facilities for the efficient movement of trains.

• To provide facility for safe and efficient shunting operations.

• To provide facility for max. utility of tracks.

• To ensure safety between two or more trains which cross or approach each other’s path.

HISTORY OF SIGNALLING

1825: FIRST RAILWAY LINE FOR GOODS

TRAFFIC WAS OPENED BETWEEN DARLINGTON TO STOCKTON (U.K.)

UNIFORMED MEN ON HORSES GUIDED THE TRAIN

1830 : FIRST PASSENGER TRAIN BETWEEN LIVERPOOL AND MANCHESTER

POLICEMAN WERE POSTED AT FIXED INTERVALS

CLASSIFICATION OF SIGNALS

1. OPERATING CHARACTERISTICS

2. FUNCTIONAL CHARACTERISTICS

3. LOCATIONAL CHARACTERISTICS

4. SPECIAL CHARACTERISTICS

OPERATION CHARACTERISTICS: BASED ON THE WAY OF THEIR OPERATION,

SIGNALS CAN BE CLASSIFIED AS:-

Signals

Detonating Hand Fixed

Operating

Detonating signals:- These are placed on the rails in foggy and cloudy weather when hand or fixed signals are not visible. Signals explodes with a loud sound when train passes over them.

Detonating signals

The sound of detonator draws attention of the driver to the proximity of the signals. From the safety point of view, the

detonators must be placed on the rails atleast 400 to 500m ahead of the signal to enable the driver to stop the train, or to obey the signals.These signals consists of containers with explosive and are fixed to the rails by means of clips.

This type of signalling is done manually.

Hand signals are given either by flags fixed to a wooden handle or by

bare arms when flags are not available during the day time.

These are generally used by guards, station masters, cabin man or any

other authorised man

HAND SIGNAL

During the night time, lamps are used in which movable glass slides of green, red and yellow sheds are provided.

Following are the signal conventions used:-

Serial no. Colours of flag/lights Meaning of signals

1 Red flag of light STOP

2 GREEN flag of light PROCEED

3 YELLOW light PROCEED CAUTIOUSLY

Stop or semaphore

Warner signals Shunting signals

Coloured-light signals

Functional characteristics

STOP OR SEMAPHORE

SIGNALS

The principle of design of semaphore signals is to show the stop position

Of any failure that happens to be in the apparatus.The signal mechanism is so arranged that in normal

position it indicates theStop position.

Serial no. OPERATINGTIME

POSITION OF ARM

POSITION OF SIGNAL

INDICATIONGIVEN

1 Day time 1- horizontalarm2-inclined arm45to 60 degree

“ON” position

“OFF” position

“STOP”

“PROCEED”

2 Night time 1- red light2-green light3-yellow light

“ON” POSITION“OFF” position

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“STOP”“PROCEED”“PROCEED CAUTIOUSLY”

3 Day or night time

1-no signal2-white

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“DANGER”“DANGER SIGN”

WARNER SIGNAL

A semaphore signal at the entrance to station

is combined with a warner signal.

The warner signal is similar to semaphore

signal in shape except a v-notch at free end.

The warner signal is placed on the same post

of semaphore signal at 1.8 to 2.1m below the

semaphore signal., which is of yellow colour.

Shunting signal (GROUND SIGNAL)

These signals are used for shunting

operations in stations yards and therefore ,

They are called shunting signals.

They are of the shape of a circular disc with

a red band on a white background.

The disc can revolve in a vertical plane by

pulling the lever by hand.

The following indications are given by disc or shunting signals:-

1- when the red band of disc is in horizontal position or it shows red light at nightIt indicates ‘STOP’.

2- When the red band is in inclined position or shows green light at night, it indicates‘PROCEED’.

COLOUR LIGHT SIGNAL

SPECIAL SIGNALS

REPEATER SIGNAL

CALLING SIGNAL

ROUTING SIGNAL

POINT INDICATOR

MODIFIED LOWER QUADRANT SEMAPHORE SIGNAL

REPEATER SIGNAL

COLOURED LIGHT SIGNALS

DHANYAWAD