Explained | What is the electronic interlocking system in railways?  Premium

Check out The Hindu explainer on the electronic interlocking system in railways. And what could have caused the accident in Balasore in Odisha. 

The story so far: An electronic track management system used by the railways has become the focus of investigations after last week’s horrific train crash involving two express trains and a goods train in Odisha’s Balasore district that left 275 passengers dead and more than 1,000 injured. 

Minister for Railways Ashwini Vaishnaw said a “change made in the electronic interlocking and point machine” led to the accident. On Sunday, the Railway Board recommended a CBI investigation as it identified “signalling interference” as the main cause of the accident in its preliminary probe. “The Commissioner of Railway Safety has investigated the matter… we have identified the cause of the incident and people responsible for it. It happened due to a change in electronic interlocking,” the Minister said, while insisting that the crash was not linked to the Kavach system.

The KAVACH is an indigenously developed Automatic Train Protection (ATP) system by the Research Design and Standards Organisation (RDSO) in collaboration with the Indian industry.  It is meant to provide protection by preventing trains from passing Red signals and thereby avoid collision.

Interlocking is an integral part of railway signalling. It refers to a mechanism that controls the movement of trains to ensure trains move safely through a controlled area. The system is an arrangement of signals and points, which may be inter-connected mechanically or electrically or both, which operate so that a train can move from one track or junction to another safely, without coming in the way of another train. 

Electronic interlocking (EI) is an advanced signalling, computer-based system that uses electronic components to manage the movement of trains and the configuration of tracks. The EI, which is based on software, is designed to prevent two trains from running on the same track at the same time. It ensures that a train gets a go-ahead only when the route ahead is clear. The system is an alternative to the conventional Relay Interlocking system. 

As of last year, 2,888 stations in India were equipped with an electronic interlocking system — comprising 45.5% of the Indian Railways network.

The EI signal system comprises three crucial elements: