Finally!  The MBTA officially announced what caused the Red Line derailment back in June which destroyed the signal system at the JFK/UMass stop. 

Officials believe that arcs of electricity damaged a 27-year old front axel on a Red Line train.  Evidently, inspectors didn’t notice that the coated metal rings which help to keep the axle grounded were worn down which caused electrical currents to weaken the equipment before it broke completely. 

All other Red Line trains have been checked for the same issues and removed seven axles and two ground rings because they looked like could cause potential trouble.

MBTA maintenance crews continue to work to restore the signal systems.  Fingers crossed – MBTA hopes  to see Red Line service return to normal in October.