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

A Green Line trolley was going more than three times the speed limit and failed to stop for a signal before derailing Oct. 1, officials said.

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.

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

The MBTA Green Line train that derailed near Lechmere Station earlier this month was traveling over three times the speed limit<a class="excerpt-read-more" href=" More

The train also passed through a signal requiring a stop before it hit a switch that was still in motion, according to the NTSB's preliminary report.

The train was going more than 3 times faster than it should when it failed to stop for a signal and derailed on a switch.

Speed may have contributed to an MBTA Green Line derailment in Cambridge, Massachusetts, that injured several people and snagged service for days at the beginning of the month, according to the preliminary investigative report released Wednesday.

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.