Driver May Have Tied Back Throttle of Runaway Train Department of Transportation secretary says that claim is being investigated By Evann Gastaldo, Newser Staff Posted Dec 11, 2015 1:09 PM CST 16 comments Comments Massachusetts Bay Transportation Authority commuter trains wait to start running again early Sunday, Feb. 10, 2013 in Boston. (AP Photo/Gene J. Puskar) (Newser) – After a Boston Red Line train went through four stations without a driver Thursday, the governor of Massachusetts said it had been "tampered with." The news today doesn't sound quite so sinister: The investigation is focusing on operator error, the state's Department of Transportation secretary tells WCVB. The driver, David Vazquez, who has more than 25 years of experience, was placed on administrative leave pending the results of an investigation, CBS Boston reports. Gov. Charlie Baker later said the train controls "had been manipulated, which was why the train moved without a person controlling it," and that it remains to be determined whether simple negligence or something else is to blame. On Friday, he said the driver made "multiple" errors, the AP reports, and the DOT secretary called the driver's actions "irresponsible." The MBTA is investigating along with several other agencies, the Boston Globe reports. While parked at a station, the driver said there was a signal problem and asked to put the train into "bypass mode," meaning it would be allowed to move even if it didn't get the correct signal. He had to leave the train to throw a toggle switch in order to get into bypass mode, and the train ended up leaving while he wasn't inside. It clipped him, and he reported the incident within moments. Per MBTA procedures, he should have set two brakes before exiting the train, and the DOT secretary says at least one of those had not been set. She says there are also reports the throttle had been tied back with a cord. One transportation researcher explains that it's common for subway operators to go into bypass mode rather than being forced to wait at a station if there's a signal failure, but says he doesn't know how the train would have been able to accelerate without a driver at the controls: "That's really the freakiest part," he says. "You need a person to push the throttle to move it."