Subsidiary Signals

Signals are used for reception of trains in to a station and despatch of trains out of station. Signals used for movement of trains with in the station section at restricted speed and for special purpose are called Subsidiary signals.

In MACL signalling Shunt signals and Calling–on signals come under subsidiary signals

Shunt signal :

                                   ‘ON‟ POSITION                                      OFF’ POSITION

                           Aspect                           Stop                                                  proceed slow-

                     Indication                  Stop dead                              proceed with caution for shunting

It is of position light type, The lights shall be white in colour. Shunt signals control shunting movements.

A shunt signal may be placed on a post by itself or below a stop signal other than the first stop signal of a station.

When a shunt signal is taken „OFF‟, it authorizes the driver to draw ahead with caution for shunting purposes although stop signal, if any, above it is at „ON‟.

When a shunt signal is placed below a stop signal, it shall show no light in the „ON‟ position.

Calling-on signal

A Calling-on signal has no independent location and displays no aspect in „ON‟ position. A calling-on signal where provided, shall be fixed below a stop signal governing the approach of a train with „C‟ marker board fixed to the signal post. A calling-on signal when taken „OFF‟ it displays a miniature yellow light.Under approved special instructions, a calling-on signal may be provided below any other stop signal except the last stop signal.

When placed below a stop signal, it shall show no light in the „ON‟ position. A calling-on signal under main signal above it cannot display “OFF” aspect at same time.

Railways Subsidiary Signals | Shunt signal | Calling-on signal

Types of Signals :- Signal is a medium to convey a particular pre-determined meaning in non-verbal form.

Multiple Aspect Color Light Signal (MACLS): Multiple means more than 2 indications .They may have 3 or 4 different aspects or indications to be given to the driver. These signals have longer range of visibility and Improved reliability.

Classification of CLS:

Manual Stop Signal :

Each aspect of the signal is represented by a circle. A horizontal line inside the circle indicates Red aspect, an inclined line the yellow aspect and vertical line the Green aspect. The normal aspect of the signal is shown by double line.

Permissive Signal (Distant Signal):

Shall be located at an adequate distance in rear of the stop signal, the aspect of which it pre- warns. The normal aspect of permissive signal is „Single Yellow„ where 2 distant signals are provided to pre- warn the stop signal, the outer most signal, to be located at an adequate distance from the first stop signal, shall be called the distant signal and the other called the inner distant signal, with the distant capable of displaying „ attention „ or „ proceed‟ aspect only .

To distinguish between stop signal and permissive signal „ P „marker board (letter in black on white board) is fixed to the permissive signal.

Automatic Stop Signal :

The normal aspect of an automatic signal is green and is indicated by the double vertical line, unlike the manual signal where the normal aspect is red and indicated by double horizontal lines. An automatic signal has an „A‟ marker plate fixed to the signal post to distinguish it as an automatic signal. Letter „A‟ in black on white circular disc.

Semi-automatic Stop Signal :

An illuminated „A‟ marker distinguishes a semi – automatic signal from a fully automatic signal. Letter „A‟ against black back ground is illuminated when working as an automatic stop signal and letter „A‟ extinguished when working as a manual stop signal.

Markers & boards

Warning Board: Provided to warn the driver that he is approaching a stop signal. To
draw attention of the driver in the night, self-reflecting sheets are fixed. It is located not
less than 1.5 Kms. in rear of FSS. Where double distant is provided, warning board is
dispensed with.

Shunting Limit Board

Provided on single line sections where shunting in the face of
approaching train is permitted. Placed at a distance not less than 180 Mts. from the
opposing First stop signal.

Block Section Limit Board

Provided on double section where there are no facing points or the outer most points at the approaching end are trailing. It shall be placed at a distance not less than 180 Mts. from the first stop signal.

Outlying Siding

Where an intermediate siding taking „OFF‟ in the facing direction in passenger running line outside station limits is provided with „S‟ marker board to indicate  that a siding is taking „OFF‟ from main line.

Markers & boards | Shunting Limit Board |  Block Section Limit Board | Outlying Siding