When trolleys collide

Jemima was in the front of the trolley train rear-ended by another trolley between Copley and Arlington this morning (in an accident that Channel 5 helpfully tells us was Not Related In London Attacks). She reports:

... It felt like we ran over something. Our hardy train continued on to Arlington where we stood for a while. Then the police and the firemen started coming down into the station, and the conductor tossed us all out with a vague promise of buses upstairs. (I didn't start riding the T yesterday, lady!)

More firemen were swarming upstairs and on the street, and they treated one conductor, who seemed shaken but unhurt. I hung around for a bit eavesdropping on the firemen to figure out what happened, even though I was worried about being so close to the T entrance and whatever smelled like it was burning down there. Once I heard it was a collision (and not a squishing or a bomb or smallpox) and the TV cameras showed up, I started walking to Park Street. ...