A preliminary investigation into the derailment of the Kolkata-Sairang Express at Digaru railway station in Assam on November 11 has pointed to a possible failure of the train’s main braking system, with a closed brake pipe angle cock suspected to have prevented the brakes from functioning, PTI reported.
According to a six-member probe team’s preliminary findings cited by PTI, the BP angle cock, a component that controls the flow of compressed air required to apply brakes across the coaches, was found in an isolated condition in the locomotive.
A joint note prepared by the team on the day of the accident said this could have been the reason for the derailment, as the brakes might not have been applied while the locomotive’s FP/BP angle cock remained isolated.
The note also recorded that the train crew had applied the brakes, but they might not have worked because the angle cock was already in the closed position.
The preliminary findings do not establish who rendered the braking system dysfunctional or whether the crew failed to check its functioning before operating the train.
The loco pilot, assistant loco pilot and guard, in their statements, said the braking system was working properly when they took charge of the train at Guwahati at around 5.30 am on November 11, according to the report cited by PTI.
The train had earlier been stopped at Panbari station at 6.16 am after the wheels of one coach overheated due to jammed brake pads. The crew attended to the problem, and the train remained at the station for around 30 minutes.
It resumed its journey at 6.46 am. As it approached Digaru station, the station master directed it to enter the loop line and stop to allow another train to pass.
However, when the crew attempted to brake, the system allegedly failed. The train overshot the red signal, struck a dead end and derailed.
Safety experts cited in the report said the crew might have relied on the train’s alternative regenerative braking system to regulate its speed during the journey. They may have attempted to use the main braking system while approaching the loop line, only to find it non-functional.
One safety expert questioned who had isolated the main braking system and whether railway staff had closed the angle cock while attending to the jammed brake pads at Panbari station but failed to reopen it before the train resumed its journey.
The expert said the sequence of events made the involvement of an outsider unlikely and called for a thorough investigation.
Advisories issued by some railway divisions after the accident have also raised the possibility that the angle cock was closed during the repair work at Panbari and was not reopened before the train departed, PTI reported. This, however, remains an unconfirmed explanation.
(With inputs from PTI)