MBTA August 2, 2021 7:20 pm NTSB: MBTA Train Involved in Crash Was Going 30 MPH Investigators say a trolley was going 30 mph when it rear-ended another Green Line train going 10 mph. US & World Videos 2:31 Billerica police sergeant killed in crash honored at funeral 2:05 MIT monitors pair of opposing protests on campus 3:41 Cool air to linger over Boston into the weekend 2:01 Remembering Billerica police Sgt. Ian Taylor 3:17 Cooling back down, weekend turns wet in Boston