The NTSB revealed new details about the derailment, including naming several factors that may have played a role, such as speed.

The Green Line train that came off the tracks and injured 7 people earlier this month was traveling 25 miles over the speed limit prior to the derailment, the NTSB released Wednesday.

A Green Line trolley was speeding and failed to stop for a signal before derailing near Lechmere Station Oct. 1, officials said Wednesday. The post Green Line train was going 36 mph in a 10 mph zone when it derailed,

The Green Line train that derailed at the beginning of October was going 36 mph in a 10 mph zone, a preliminary investigation shows.

A preliminary report suggests that speed was likely a factor in a Green Line train derailment earlier this month, which resulted in a multiple-day closure.