Two trolleys collided on Boston’s Mattapan High-Speed Line at Cedar Grove Station, injuring 17 passengers and damaging the two cars involved. According to Boston Fire Department spokesman Steve MacDonald, two trolley cars that were traveling inbound had collided. He said the collision had occurred on a stretch of tracks that was flanked by the Cedar Grove Cemetery on one side and a river walkway on the other. The line relies on a fleet of 10 PCC trolleys that were rebuilt more than 10 years ago. The cause of the accident remains under investigation.