State and federal officials launched an investigation after the driverless train sailed through four stations and more than 5 miles with about 50 passengers on board. On Friday, Governor Charlie Baker and state transportation officials vowed to avoid a similar situation in the future, and sought to portray the incident as an “unacceptable,” but highly unusual anomaly caused by several errors by the driver.

The operator of the Red Line train that took off from Braintree without him Thursday had apparently rigged a cord around a throttle used to control the train’s movement and also failed to set the brake before exiting the vehicle, according to an official familiar with the investigation’s preliminary findings.


“We all understand the fear, the shock, surprise, that those 50 passengers must have experienced,” Baker told reporters during a Friday press conference. “We are confident that this was an isolated incident where a single individual appears to have made multiple errors.”

The unmanned subway train is the latest in a string of controversies for the Massachusetts Bay Transportation Authority, an agency still struggling to regain public confidence after it faltered amid last winter’s historic snows.

MBTA officials met with the state Department of Public Utilities and the Federal Transit Administration on Friday morning, as the investigation continued.

Baker and his transportation secretary, Stephanie Pollack, did not confirm that the driver had tied a cord around the control lever, but both stressed that the driver had apparently made several mistakes.

“One error would not allow something like this to happen,” said Pollack.

Pollack said the driver is on paid administrative leave and is cooperating with the investigation.

An official familiar with the case has said the driver was David Vazquez, a train operator with more than 20 years at the MBTA, though the state Transportation Department would not confirm his identity. According to documents from the MBTA, Vazquez earned $96,000 in 2014, including overtime and other pay. Vazquez could not be reached for comment Friday.


The MBTA has several “prohibited acts” that could result in firing a driver, and restricting the movement of the controller that steers the train forward is grounds for termination, according to Pollack.

Inside the MBTA’s Operations control room in downtown Boston where a dispatch team was able to bring the runaway train to a stop. A dispatcher monitored the red Line trains and the far left monitor showed the Braintree T Station stop. John Tlumacki/Globe Staff

The train in Thursday’s incident — one of the oldest in the Red Line fleet, built by Pullman-Standard in the late 1960s — is operated by a lever in the cab called a Cineston controller, which combines the accelerator, brake, and a “dead man’s” safety feature.

The train operator must press that lever down before turning it to accelerate or decelerate and must continue to press it while operating the train. If the operator releases pressure, the lever should pop up, stopping the train automatically.

On Thursday morning, the driver had apparently rigged the lever with a cord to avoid having to apply continuous pressure, according to the official familiar with the investigation.

Doing that could have thwarted the “dead man’s” safety feature that would have stopped the train from moving forward. In addition, Pollack said, the driver had not set a second brake.

At 6:08 a.m. Thursday, the operator contacted the T’s operations control center about an apparent signal problem that was prohibiting the train from moving forward and requested permission to set the train into “manual bypass” mode to override the signal system.

That required him to climb out and throw a toggle switch under the train. The train took off once the switch was flipped, officials said.


The six-car, 420-foot-long train left Braintree station, and then cruised through the Quincy Adams, Quincy Center, and Wollaston stations on a 9-minute trip. MBTA officials managed to stop it past the North Quincy Station by cutting power to the third rail.

As investigators continue to search for answers, Braintree Mayor Joseph Sullivan said he wants to know if other T operators are also rigging controls. “As an organization, the MBTA needs to discover whether or not these types of actions are a common practice or if this was just a one-off thing,” he said.

MBTA officials say they have issued a reminder to train operators about prohibited acts such as restricting the movement of the controlling lever.

Officials have not disciplined any drivers for rigging the control in a similar way in the past five years. Though Pollack said they had no reason to believe it is a “widespread practice,” they said they will look into the issue in the investigation.

James O’Brien, president of the Boston Carmen’s Union, said he was not aware of similar incidents involving a rigged lever.

Far less rare are the signal problems that forced the driver to ask for permission to go into “bypass mode.” Jeffrey Gonneville, chief operating officer of the MBTA, said the MBTA deals with signal problems about half a dozen to a dozen times a week systemwide.

To ensure that a similar incident doesn’t happen, the MBTA is now requiring a senior MBTA official — including inspectors, instructors, administrative officials, and supervisors — to be present every time a driver wants to enter bypass mode. Gonneville said that may also lead to additional delays.


“Putting trains into bypass mode is something that’s going to be watched very closely,” he said.

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Nicole Dungca can be reached at nicole.dungca@globe.com. Follow her on Twitter @ndungca. Eric Moskowitz can be reached at eric.moskowitz@globe.com. Follow him on Twitter @GlobeMoskowitz.