New Orange Line trains back in service following investigation into braking problem

BOSTON — Six new Orange Line trains returned to service Monday morning following a four-day investigation into a braking issue, the MBTA said.

A train experienced a problem in one of its 48 braking units at Wellington Station last week and the MBTA removed all new cars from service while engineers and technicians worked to determine what caused the problem, transit officials said.

In a statement, the MBTA said, “Preliminary findings indicate that one bolt in one of the car’s eight braking units had not been properly installed at the manufacturing plant.”

The MBTA noted that the issue was not found in any other braking units.

This is a developing story. Check back for updates as more information becomes available.

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