​On February 9, 2025, about 12:22 a.m. local time, westbound Massachusetts Bay Transportation Authority (MBTA) light rail train 3840-3698 (striking train), collided with the stationary MBTA light rail train 3851-3663 (out-of-service train), damaging four cars and derailing one car on each train at East Somerville Station in Somerville, Massachusetts. [1] (See figure.) There were two crewmembers and six passengers on the striking train and two crewmembers on the out-of-service train. Two passengers and four crew members sustained non-life-threatening injuries. MBTA estimated damages to equipment to be about $6.6 million. Visibility conditions at the time of the accident were dark and snowing; the temperature was 26°F.         ​

​The crew of each train included one streetcar motorperson (SCMP) operating the train from the lead (west) end cab of the lead car, and one SCMP in the west end cab of the second, trailing car. The accident site had two main tracks on opposite sides of the passenger platform at the station. Each train consisted of two cars coupled together, and both were operating on the Green Line E. Train movements were authorized by signal indication and coordinated from MBTA’s Operations Control Center located in Boston.

Shortly before the accident, the striking train departed Medford/Tufts Station and made three station stops without incident before approaching East Somerville Station, where the out-of-service train was stopped awaiting routing into MBTA's Inner Belt Yard. A preliminary review of event recorder and signal data indicates the striking train was traveling about 32 mph when it entered a 25-mph zone, passed a red (stop) signal and entered the 10-mph zone in the station where it collided with the stationary out-of-service train.

While on scene, National Transportation Safety Board (NTSB) investigators examined the track conditions and signal system; performed mechanical evaluations; retrieved and reviewed data from the event recorder, surveillance cameras, radio ​communication recordings, and signal logs; and conducted interviews.

The NTSB’s investigation is ongoing. Future investigative activity will focus on vehicle crashworthiness; human performance; internal and external safety oversight; and operating procedures.

Parties to the investigation include:

• the Federal Transit Administration; 
• the Massachusetts Department of Transportation; 
• the Massachusetts Department of Public Utilities; 
• MBTA; and 
• the Boston Carmen’s Union, Local 589.