The Red Line resumed regular service Wednesday, one day after a derailment at the Broadway station in South Boston that forced commuters to use shuttle buses between downtown Boston and Dorchester for more than 12 hours.
The cause of the derailment remains under investigation, T spokesman Joseph Pesaturo wrote in an e-mail Wednesday.
A speed restriction is in effect due to continuing safety concerns, the T tweeted Wednesday.
On Sunday, an ascending escalator at the Back Bay station suddenly reversed, causing a bloody pile-up of people that sent nine to the hospital. Earlier this month, Boston University professor David K. Jones fell to his death through a gap in a rusted, closed-off staircase near the JFK/UMass T station in Dorchester. And in July, a Green Line train crashed into a train ahead of it near the now-closed Pleasant Street Station, sending 27 people to the hospital.
The operator of the Green Line trolley in the Pleasant Street crash is facing criminal charges in Brighton Municipal Court, following an investigation by Transit Police. Owen T. Turner of Boston is charged with gross negligence of a person in control of a train, and gross negligence of a person having care of a common carrier, according to court records. He is scheduled to be arraigned Oct. 6.