Railway signalling: Back From precision to peril: Role of signalling in train accidents

Source: The post is based on the article “Back From precision to peril: Role of signalling in train accidents” published in the Live Mint on 6th June 2023

What is the News?

Preliminary investigations into the three-train crash in Odisha point to a signalling error and interference with the electronic interlocking system.

How does railway signalling work?

Signalling method: The signalling system in India is automatic. There is little manual intervention now. Indian Railways is moving to a uniform signalling system called ‘electronic interlocking (EI)’. EI is a network of signals and switches—which would control the movement of trains.

Signalling types: Signalling has two main parts: one dealing with the movement of trains between stations and another within a station.

a) Movement of trains between two stations: It is governed by ‘block rules’. The track is divided into blocks electronically, with signalling at both ends of the block.

b) Movement of trains within stations: It is regulated by ‘interlocking’. It ensures trains aren’t set on a collision course with the right signalling and alignment of points—the place where a train change tracks.

If a part of the track or the loop line is already occupied by a train, the interlocking system ensures the signal for the approaching train is not cleared.

What are the errors faced while railway signalling?

The electronic interlocking of signals will face challenges like a) external interference (like sabotage), b) system lapses and c) software glitches.

Electrical signalling derives its power using underground cables. Faults there could alter EI functioning.

Is railway signalling mostly at fault in train collisions?

As per a report by the Comptroller and Auditor General last year, out of 2,017 train accidents between 2017-18 and 2020-21, 1,392 or 69% were due to derailment. Further analysis of derailment revealed 24 factors are responsible for derailment. This includes an incorrect setting of points at stations, and systems and technological deficiencies in signalling systems.

How can train travel be made safer?