NEW DELHI: A preliminary railway probe into the derailment of the Kolkata-Sairang Express at Digaru station in Assam on Wednesday has pointed to an isolated brake system in the locomotive as a possible cause of the accident, according to a joint note prepared by a six-member investigating team.
The team found that the FP/BP angle cock, a valve that controls airflow through the train's braking system, was in an isolated position in the locomotive. "The brakes may not have been applied when the FP/BP angle cock of the loco was in an isolated condition," the note said. It added that the crew had applied the brakes, but they may not have worked because the valve was closed.
The report does not identify who isolated the system or establish whether the crew failed to check it before starting the journey. In their statements, the loco pilot, assistant loco pilot and guard said the brakes were working when they took charge of the train at Guwahati around 5:30 am.
According to the probe, the wheels of one coach overheated because of jammed brake pads, prompting the train to stop at Panbari station at 6:16 am. The crew attended to the problem, and the train remained at the station for about 30 minutes.
It resumed its journey at 6:46 am. As it approached Digaru, the train was signalled to enter a loop line to allow another train to pass. However, the brakes did not respond when the crew applied them. The train overshot a red signal, hit the dead end and derailed.
Safety experts cited in the report suggested that the crew may have been using regenerative braking to control the train's speed and discovered that the main braking system was not working only when they attempted to stop. Regenerative braking uses the train's traction motors to help slow it down.
Advisories issued by some railway divisions after the accident suggest that railway staff may have closed the angle cock while attending to the jammed brake pads at Panbari and failed to reopen it before the train resumed its journey. However, the preliminary probe has not established who isolated the valve.
(with inputs from media organisations)