NTSB: Short circuit probable cause of MBTA passenger death

The National Transportation Safety Board this month identified a short circuit as the probable cause of a passenger death on the Massachusetts Bay Transportation Authority’s Red Line in April 2022.

The accident occurred early on April 10, 2022, as a rider at the Red Line Broadway Station was caught in the doors of rail-car 1510 of train 1034 and dragged to his death, according to the incident report and analysis.

NTSB investigators found that the propulsion system on the rail car was enabled even if a door was still open. Further testing showed that a short circuit in the rail car’s electrical system bypassed the passenger door interlock circuit, which is meant to prevent movement if a door is not fully closed.

Protruding wire strands on the terminal board underneath the rail car’s Cineston master controller were touching a mounting screw, completing the short circuit. The master controller had been rebuilt in 2017; the short circuit is assumed to have occurred sometime after that, according to the report.

The train operator did not violate any work rules during the incident, NTSB officials wrote in the report. However, after physically looking outside the cab to ensure platform clearance before departure, the operator pulled her head back into the operating cab before the pilot lights above the doors had turned off, contrary to departure procedures. The pilot lights turn off once doors are fully closed.

Additionally, the operator had received multiple warnings for attendance and disciplinary action for a door failure in a previous accident. The operator was disciplined after failing to stop for a double red signal and finished a reinstruction course five months before the Red Line accident.

No drugs or alcohol were detected on a post-accident test, NTSB officials said.

Other tests revealed a 19-foot blind spot for single-person train operator cameras looking at the station platform, which would have included the doors the rider used. However, NTSB investigators did not find any physical line-of-sight obstructions.

A review of MBTA’s fleet preventative maintenance inspection procedures showed that there was no inspection protocol for the functionality of the door interlock circuit. Following the accident, MBTA updated its procedures for door obstruction and interlock testing to verify that train movement would not occur with open doors. Additionally, the Federal Transit Administration took on an increased safety oversight role following the accident and began conducting safety management inspections of MBTA operations and maintenance programs.

MBTA expects to retire the 1500 series of rail cars by March 2024.