NTSB: Short Circuit Probable Cause of MBTA Passenger Fatality

Written by Carolina Worrell, Senior Editor
NTSB photo

NTSB photo

The National Transportation Safety Board (NTSB) recently determined that the probable cause of an April 10, 2022, Massachusetts Bay Transportation Authority (MBTA) passenger fatality was a short circuit in the passenger door interlock circuit on the accident railcar that “enabled propulsion on MBTA Red Line train 1034 with the door obstructed by a passenger, causing the passenger to be dragged along the platform.

In this accident, an MBTA passenger was dragged and killed when the passenger doors of railcar 1510 closed on his upper body and the train departed Boston’s Broadway Station. Post-accident examinations and testing, according to NTSB, found a short circuit in the electromechanical contact connections under the Cineston master controller in the lead car.

According to NTSB, under normal operating conditions, the passenger door interlock circuit “would have prevented train propulsion if a door obstruction was detected or the doors were open.” However, the short circuit that bypassed the passenger door interlock circuit “allowed the train to proceed even with the passenger’s upper body obstructing the accident railcar doors,” NTSB stated in its investigation report. The railcar passenger doors were designed to become secure in their positions at a train speed of 3 mph or higher. When train 1034 accelerated to leave the station, it quickly reached 3 mph, and the doors became secure in their positions, leaving the passenger unable to free himself.

NTSB investigators determined that the short circuit bypassing the passenger door interlock circuit occurred sometime after the 2017 Cineston master controller rebuild. As a result of the accident, MBTA implemented a method to “electrically isolate wire terminal contacts and mounting screws on the Cineston terminal board and updated its door obstruction and door interlock testing procedures.”

MBTA, according to NTSB, plans to retire its 1500 series railcars from service by March 2024.

On April 13, 2022, following the accident at Broadway Station, the Federal Transit Administration (FTA) notified MBTA that it would “immediately assume an increased safety oversight role of the MBTA system.”

The FTA, according to NTSB, further notified MBTA that FTA Transit Safety Oversight would “conduct a safety management inspection of transit operations and maintenance programs and would assess the effectiveness and role of the Massachusetts Department of Public Utilities (DPU),” the state agency responsible for safety oversight of the MBTA’s rail transit operations.

On June 15, 2022, the FTA issued special directives to MBTA and the DPU to address interim findings of patterns of safety incidents uncovered during the safety management inspection.

The FTA also issued Safety Advisory 22-1, titled Rail Car Passenger DoorInspection and Function Testing, on October 13, 2022.

According to NTSB, the FTA recommended that state safety oversight agencies “direct rail transit agencies operating rail fixed guideway public transportation systems to evaluate the sufficiency of railcar passenger door inspection and function testing procedures.”


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