The employee placed on leave was operating the first car of the two-car trolley that struck the other two-car train from behind.
The operator was not identified by the MBTA.
MBTA Expert Says Trolley Accidents Like Friday's Crash Typically Caused By 'Human Error'
WBZ CBS Boston
MBTA expert Carl Berkowitz said although the cause of the crash is under investigation, trolley accidents are typically caused by..
