What led to derailment of Kolkata-Sairang Express? Main brake failure, missed safety checks under probe

The derailment of the Kolkata-Sairang Express train near Guwahati on November 11 brought the train’s braking system and mandatory safety checks under review, with a preliminary examination pointing to a malfunctioning main braking system, PTI reported.

The six-member probe team found that the brake pipe (BP) angle tap, a key component responsible for braking the coaches, was in an isolated condition inside the locomotive. The preliminary findings raised questions about whether the train staff had carried out the prescribed braking tests before the train was run.

The Railway Board has since directed all zonal railways to ensure that crews carry out brake tests after taking over a train. It also ordered a safety drive from November 12 to 18 to check compliance with braking and braking performance tests.

How did the main brake system become inoperable?

According to officials quoted in the PTI report, a possible communication gap between the station staff and the train staff could have led to the isolation of the BP corner tap.

The Kolkata-Sairang Express used to stop at Guwahati where its electric locomotive was routinely replaced by a diesel locomotive. During this process, station personnel would isolate the BP corner tap.

However, after the electrification of the route was completed, the practice of replacing locomotives at Guwahati was discontinued. An electric locomotive started running the train behind the station.

An official told PTI that the employee responsible for isolating the corner tap was off when the locomotive exchange was interrupted. When he returned to service on November 11, he is said to have followed earlier procedure and isolated the corner cock, apparently unaware that the same electric locomotive would continue the journey.

The probe’s preliminary report did not identify who caused the brake system to malfunction or whether the train crew failed to follow required safety procedures.

Did the train crew miss the mandatory braking tests?

An official quoted by PTI said the crew either did not conduct the mandatory braking tests or relied on an alternative regenerative braking system to check the braking performance of the train.

The crew could only discover that the main braking system was not working when they tried to stop the train near the loop, the official said. This may have contributed to the derailment.

The Railway Board’s latest directive has reiterated the requirement that locomotive crews conduct two tests – a brake feel test and a braking performance test.

During the braking test, the crew first accelerates the train to 15 km/h and activates the brakes by reducing the brake line pressure using the A-9 main brake system. The speed should drop to approximately 10 km/h to allow the crew to assess whether the brakes have been applied effectively.

To test the braking force, the locomotive pilot accelerates the passenger train to 60-70 km/h before braking. The speed should then drop to 30-35 km/h. For freight trains, the prescribed test speeds are 40-50 km/h and 20-25 km/h.

The Railway Board has also specified the duties of an assistant locomotive pilot. The assistant must check the tests, ensure their execution by the locomotive pilot and, if necessary, remind the pilot.

What did the Railway Board order?

In its November 11 communication, the board asked all the zonal railways to ensure that the driving crews after handing over the trains carry out brake tests in accordance with the laid down procedures.

It also ordered a safety run between November 12 and 18 to verify that locomotive crews were carrying out brake and brake force tests. Any discrepancies found during the exercise must be compiled and sent to the Railway Board by November 20.