State Rep. Mike Connolly expressed concern about the incident, saying “it could have been much more catastrophic.”

The MBTA is investigating how “human factors,” including the train operator’s action, could have been involved with the incident. The post Train operator might have caused Green Line train derailment at Lechmere,

The shuttle buses that replaced train service all day Wednesday have been phased out, the MBTA said in a social media post at about 10:30 a.m. Thursday.