‘Boom’ Causes Orange Line Scare

The train made a loud noise, and passengers were asked to exit the vehicle.

Morning commuters were rattled by a “boom” and then quickly evacuated from an Orange Line train at State Street on Thursday, after an airbag exploded in the undercarriage of one of the train’s cars.

Initially, when asked by Boston, a T spokesman said that an overheated train motor caused the loud noise that startled riders. “That was the initial report from the field,” said Joe Pesaturo. Officials on scene probing the incident also said they were looking into the possibility that something fell onto the tracks, and was struck by the incoming train, he said.

In the end, officials determined it was the airbag’s unexpected deployment that led to the loud banging and service disruption. “The airbags on subway cars are similar to shock absorbers on motor vehicles,” Pesaturo said, explaining where the noise generated from.

The MBTA confirmed that the Orange Line train was taken out of service, and moved from State Street station for examination at the time of the incident. “I was in another carriage and didn’t see much. Everyone left calmly —it was just loud and smoky,” one rider told Boston.

The train’s mishap prompted a response and the need for assistance from the Boston Fire Department, who headed to the scene at State Street as reports rolled in about the loud noise and evacuation. The train, however, kept moving on its own toward the T’s Forest Hills stop, according to transit officials.

Shortly after the incident, riders started Tweeting about what happened during their ride to work: