Automatic Signalling

 Automatic Block System 

A) Automatic Block is a system in which movement of trains is controlled by the stop signals which are operated automatically by passage of trains past the signals.

B) The automatic stop signal which governs entry of train into an Automatic Signalling section is a multiple aspect colour light signal which is not dependent upon manual operation but it is controlled automatically by the passage of a train into, through and out of the automatic Signalling  section which the Signal governs.

C) The line between two adjacent crossing stations shall be divided into a series of signalling sections and entry into each signalling section shall be controlled by a manual stop signal or Automatic Stop Signal which must assume ON position on entry of a train into the section and be maintained in that position until the train has passed clear of the next Automatic Stop Signal in Advance and also for an adequate distance beyond it. 

D) No automatic signal shall assume OFF position unless the line is clear not only upto the next Stop Signal but also for an adequate distance beyond it.

If Next Stop Signal is Automatic , the this adequate distance is 120 m.

If Next Stop Signal is Manual or Semi automatic , the this adequate distance is 180 m.

E) The signal that governs entry into Block Section shall be Manual or Semi-automatic Stop Signal 🚦.

Manual Stop Signals

Fixed Signals which require manual control each time they are taken OFF are called Manual Stop Signals.Manual Stop Signal shall be manually operated signal which shall assume ON position automatically on occupation of the section ahead but shall assume OFF position only when they are operated.

Semi automatic Stop Signal

A fixed signal having both manual and track circuit control and which is capable of being operated either as an Automatic Stop Signal or manual Stop Signal, is called Semi automatic stop signal.

Important points regarding Automatic 

1) passage of trains Duties of Loco Pilot and Guard when an Automatic Stop Signal on Single line is to be passed on Danger-GR 9.07.

2) Automatic signal Interlocked with a LC gate shall be provided with a yellow disc with letters G in Black and an A marker light.

3) The A marker shall be lit only when the gates are closed and locked against road traffic.

4) In 4 aspect automatic block section, one track section plus overlap is required to be clear to get Caution ( Yellow) aspect.

5) When a Loco pilot finds an Automatic Stop  Signal  with an A marker at ON. He must stop and in rear of Signal can pass this  ON Aspect  after waiting One minutes at day and two minutes at night.

6) Minimum 4 trains can be there at a time in a Automatic Section.

7) Overlap is 120 m for every signal in Automatic. For Home signal, it is 180 m as usual.

8) There is no Automatic signalling in Station Section.

9) Home Signal can be made Semi Automatic by placing illuminated A marker.This A marker will lit through a switch by Station Master when Home Signal fails and then this Home Signal will work like Automatic and driver will pass through it.

10) Immunisation of A marker shall prove that correct setting and locking of the points as required and ensures the back locking of routes.

11) Passing a Gate Stop Signal at ON in Automatic Signalling- GR 9.15.

12) If the A marker is extinguished, he shall sound the prescribed code of whistle to warn the gateman and bring the Train to stop in rear of Signal. After waiting 01 minutes in Day and 02 minutes in night. He shall pass the cautiously.

Essentials of The Automatic Block System on Double Line - 

Where trains on a double line are worked on the Automatic Block System.

A) The line shall be provided with continuous track circuiting or Axle counter.

B) The line between two adjacent Block Stations  are divided into series of Automatic Block signalling sections each of which is the portion of running line between two consecutive stop signals and the entry into each of which is governed by a stop signal.

C) The track circuits or Axle  counter shall control the Stop Signal governing the entry into Automatic Block Signalling Section that the Signal should not assume an OFF Aspect unless the line is clear upto next stop signal in advance and adequate distance beyond it,The Automatic signal shall be placed to ON , as soon as it is passed by train.

When a Gate Stop Signal is Semi Automatic Stop Signal and Protects Points

When a Gate Stop Signal is semi- automatic Stop Signal and protects point where exist in addition to the level crossing, it shall be provided with white illuminated letter 'A’ and white illuminated letter 'AG' against black background.The Indication of such Signal shall be as under-

A) Letter A shall be lit only when the gates are closed and locked against road traffic and points where exist are correctly set and locked for route.

B) AG will lit when  points  are correctly set and locked for the route.

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