The MBTA has released surveillance footage of the incident at the Boylston stop in which two trains collided while entering the station. In the video clip, you see a train already parked and accepting passengers. At around the 0:18 mark, the train suddenly lurches forward about six feet as a result of getting rear-ended by the trolley behind it.
It’s obvious in the clip that the collision was a violent one, and not just a light “bump” as the wording of the MBTA’s report might suggest. It’s now clear why three dozen people sustained injuries in the accident.