Driverless Red Line train had cord tied around throttle, unsecured brake

The operator of the Red Line “ghost train” that left Braintree Station without an operator on Thursday is said to have tied a cord around the train’s throttle, according to a report from FOX 25.

Investigators on Thursday made “operator error” the focus of the probe into how the train ended up leaving Braintree station early that morning without an MBTA driver at its helm. FOX broke the story Friday morning.

The operator, a 51-year-old who had worked with the MBTA for more than 25 years, has been placed on paid leave while an investigation is underway, officials said.

About 50 passengers were on board the train as it traveled north before stopping past North Quincy station without a driver, Transportation Secretary Stephanie Pollack said in a news conference Thursday night.

The trouble began when the train stopped during a signal error at Braintree station, MBTA Chief Operating Officer Jeff Gonneville told reporters on Thursday.

The driver received approval to exit the train, then flipped a “bypass” switch, designed to allow the train to travel pass the signal, Gonneville said. But then the train pulled away without a driver.

The driver sustained minor injuries when he was clipped by the train, MBTA spokesman Joe Pesaturo said. No passengers reported injuries, Pollack said.

Gonneville said train overseers knew in about 60 seconds that the driverless train had pulled away and began moving other trains further down the track out of the way. In fewer than 10 minutes, after the T cut power to the electrified third rail, the train came to a stop, Pollack said.

Metro Boston will have more on this when more information is available.