In the video taken by a rider Monday afternoon on the D branch of the Green Line, the man is seen slouched over with his head down as the trolley enters a tunnel.
A spokesman for the Massachusetts Bay Transportation Authority says the worker was in the second car of the train and was not actually in control at the time.
The two-year employee has been suspended pending an investigation and faces disciplinary action, including losing his job.
The T said such “egregious behavior will not be tolerated.”
The T has an aggressive fatigue-awareness program that is required for many employees.