Explained: What Is Electronic Interlocking? The System Linked With The Odisha Triple-Train Collision

In railways, interlocking refers to an arrangement of signals, points and appliances managed using a panel or lever to ensure that trains are operated in a proper sequence and accidents are avoided.

Electronic interlocking was earlier known as solid-state interlocking. It is a computer-based interlocking that occupies less space, consumes less power, is more reliable, and is easier to install and maintain, compared to other interlocking methods. 

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Odisha Train Accident: Sandeep Mathur, Principal Executive Director Of Signalling of India's Railway Board, said Sunday that the cause behind the deadly three-train accident which recently occurred in Balasore, Odisha, could be related to a change in the electronic interlocking system of railways. He told news agency ANI that the interlocking system signifies whether a railway track is occupied or not. The interlocking system is important to ensure that railway accidents do not occur. 

The collision of the trains, which occurred on June 2, 2023, has claimed over 280 lives, and injured more than 1,000 people. The trains involved in the collision were two passenger trains, the Coromandel Express and the Bengaluru-Howrah Superfast Express, and a freight train near the Bahanaga Bazar railway station. The 2023 Odisha train collision is India's worst railway accident since the 1995 Firozabad rail disaster, which occurred in Uttar Pradesh. 

What is electronic interlocking?

In railways, interlocking refers to an arrangement of signals, points and other appliances managed using a panel or lever to ensure that trains are operated in a proper sequence and accidents are avoided. A point is a junction of two railway lines that can be set to guide a train toward one of two alternative routes, or allow two railway lines to merge into one. A point facilitates the diversion of a train from one railway line to another.  

A railway signal provides instructions and warnings to the train's driver, and helps ensure there is no railway traffic.

According to the Indian Railways, the basic principles of interlocking include: a train can take off for a running line only when all the points on the line are correctly set, and the facing points have been locked; and all the points giving access to the running line from side lines and goods lines are set against the running line, among others. 

After the signal has been displayed, the points must not be altered, and the gate lever must not be unlocked unless the signal is put back. 

Interlocking is of different types: mechanical, electrical, electro-mechanical and electronic interlocking. 

Mechanical interlocking uses levers, while electrical and electro-mechanical interlocking use relays or circuits.

Electronic interlocking was earlier known as solid-state interlocking. It is a computer-based interlocking that occupies less space, consumes less power, is more reliable, and is easier to install and maintain, compared to other interlocking methods. 

It has several advantages over relay interlocking, which involves the use of electromagnetic devices to convey information from one circuit to another, in order to help detect whether a track is occupied or not, and lock points and signals accordingly. 

Electronic interlocking is faster than relay interlocking, allows multi-mode operations, and is a fail-safe technique. It reduces man power, allows a significant reduction in traffic block time, and has a simpler operation and consumes less power than conventional relay interlocking.