The Kolkata-Sairang Express derailed near Guwahati on November 11 due to a main brake failure. A probe showed the brake pipe angle cock was isolated, possibly because of a communication gap among staff. The Railway Board started a safety drive from November 12 to 18 to check all trains.

A preliminary probe into the Kolkata-Sairang Express derailment points to an isolated main braking system, possibly due to a communication gap among railway staff. The Railway Board has ordered safety checks across all zones.

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

A six-member probe team found that the brake pipe (BP) angle cock, a key component responsible for applying brakes in the coaches, was in an isolated condition in the locomotive. The preliminary findings have raised questions over whether the train crew conducted the prescribed braking tests before operating the train.

The Railway Board has since directed all zonal railways to ensure that running crews conduct braking tests after taking charge of a train. It has also ordered a safety drive from November 12 to 18 to check compliance with brake feel and brake power tests.

How did the main braking system become dysfunctional?

According to officials cited in the PTI report, a possible communication gap between station staff and the train crew may have led to the BP angle cock being isolated.

The Kolkata-Sairang Express earlier halted at Guwahati, where its electric locomotive was routinely replaced with a diesel locomotive. During this process, station staff would isolate the BP angle cock.

However, after electrification of the route was completed, the practice of changing locomotives at Guwahati was discontinued. The electric locomotive began operating the train beyond the station.

An official told PTI that the staff member responsible for isolating the angle cock was on leave when the locomotive interchange was discontinued. When he returned to duty on November 11, he reportedly followed the earlier procedure and isolated the angle cock, apparently unaware that the same electric locomotive would continue the journey.

The preliminary probe report has not established who rendered the braking system dysfunctional or whether the train crew failed to follow the required safety procedures.

Did the train crew miss mandatory braking tests?

The official cited by PTI said the crew may either have failed to conduct the mandatory braking tests or relied on the alternative regenerative braking system while checking the train's braking performance.

The crew may have discovered that the main braking system was not functioning only when they attempted to stop the train near the loop line, the official said. This may have contributed to the derailment.

The Railway Board's latest direction has reiterated the requirement for locomotive crews to conduct two tests -- the brake feel test and the brake power test.

During a brake feel test, the crew first brings a train to 15 kmph and applies the brakes by reducing brake pipe pressure using the main A-9 braking system. The speed should fall to around 10 kmph, allowing the crew to assess whether the brakes have been applied effectively.

For the brake power test, the locomotive pilot accelerates a passenger train to 60-70 kmph before applying the brakes. The speed should subsequently fall to 30-35 kmph. For goods trains, the prescribed test speeds are 40-50 kmph and 20-25 kmph, respectively.

The Railway Board has also specified the responsibilities of the assistant loco pilot. The assistant must monitor the tests, ensure that the locomotive pilot conducts them and remind the pilot if necessary.

What has the Railway Board directed?

In its November 11 communication to all zonal railways, the board asked them to ensure that running crews conduct braking tests after taking handover of trains, in accordance with established procedures.

It also ordered a safety drive between November 12 and 18 to verify whether locomotive crews are carrying out brake feel and brake power tests. Any discrepancies identified during the exercise must be compiled and sent to the Railway Board by November 20.