Passengers on the MBTA's Green Line experienced severe delays on Sunday due to a derailed train at the Boston College Station.
MBTA officials said a trolley traveling at a low rate of speed derailed at the station at 3:30 p.m. because an operator threw the switch before the trolley had crossed over to the other track.
Crews were able to get the trolley back on the track by 6:30 p.m.
In the meantime, buses had replaced trolleys between the Boston College Station and Washington Street.
No injuries were reported.