'Fail-safe' electronic interlocking system behind India's worst train crash in 20 years

The accident saw about 17 bogies getting derailed

The electronic interlocking system ensures that the 20,000 trains - both goods and passenger trains, running on the Indian Railways’ 120,000-km network, work seamlessly. The interlocking system has three key components - signals, crossings, and points.

A point is a moveable piece of track that changes a train’s direction and allows trains to move from one line to another, as explained in the Hindustan Times. On some of India’s busiest lines, over 100 trains will pass over just one set of points every day. Points are moved using switches operated from a control panel. Like signals, points can fail. 

A crossing is installed at a junction and performs a similar function to a point. Points, crossings, and signals communicate with each other electronically in the interlocking system.

“It is supposed to be tamper-proof, error-proof. It is called a fail-safe system, even if it fails the signal will turn red and the train will be stopped,” told Jaya Varma Sinha, a member of the Railway Board, to Reuters.

The system works in a way that it automatically changes signals or points if two trains are headed for the same path or line. But that’s not what happened on Friday. The Coromandel Express, traveling at its permitted speed of 130 km/hour, was headed for the same line on which the goods train was parked. Because there was no change in signals or points, the former rammed into the latter on the loop line near the Bahanaga Bazar station in Balasore.

A loop line is like a service lane that diverts from the main line and rejoins it at a further distance.

How did the trains collide?

The Coromandel Express jumped the tracks and four or five of its coaches at the front derailed in the event. After the coaches toppled, they hit the last two coaches of the Bengaluru-Howrah Superfast Express which was, at the same time, heading in the opposite direction on an adjacent track.

As per sources who spoke to India Today, “There was some construction work going on in the same area related to the level crossing gate. If there was a cable-faulted supply to a point, that needs to be checked. If the point was in the reverse direction, then where it should have been, that needs to be checked."

What is unsettling is that the path of the Coromandel Express had been shifted to the loop line seconds earlier and it wasn’t scheduled to stop at the Bahanaga Bazar station, said the Hindustan Times report. 

The electronic interlocking system was supposed to be tamper-proof

There are very few stations in India that have a non-electronic interlocking system. The Bahanaga Bazar station in Balasore wasn’t one of them.

“Even if this (electronic interlocking) system fails, the signals will automatically turn red, not allowing the train to continue running at the same speed,” said Sandeep Mathur, principal executive director for signaling. However, experts underlined that there is little possibility the system failed, hinting that there might have been some kind of human intervention.

“It is unlikely for a system like this to fail. In my opinion, the Chennai-bound train either derailed first and then rammed into the goods train, or there was some kind of sabotage,” further said Mathur.

The Railway Minister yesterday called for a probe by the Central Bureau of Investigation (CBI), the main investigation agency of the Indian government.