MBTA investigators are focusing on the driver in Thursday's Green Line crash that sent 37 people to hospitals with minor injuries and shut down the heart of that subway line for three hours, finding no fault with the equipment, officials said Friday.
"We have ruled out both any mechanical issues for either of the trains or infrastructure -- meaning track, signals, etc. — and so at this point we're now focused on the operator," Secretary of Transportation Richard A. Davey told reporters. "We will continue to interview the operator over the next couple of days to see exactly what happened."
The accident occurred a day before that operator was scheduled to receive a "safety pin" along with other Green Line drivers, including the one whose trolley he hit, for three straight years of driving without an accident or moving violation. Instead, he remained on paid leave and did not collect his pin, officials said.
Jonathan R. Davis, the T's acting general manager, said the operator did not seem impaired but that drug and alcohol test results had not come back. There is no evidence the driver violated the T's strict no-cellphone policy, and Davis declined to speculate whether the crash resulted from inattention, a medical incident, or human error.
"I want to be fair to our employees, and I don't want to prejudge, but we continue to have discussions with the employee that was driving this train that struck the one that was berthed," he said. "[But] there has been no claim on the equipment. In other words, the operator has not said that the brakes were not working or that the signal equipment wasn't working."
MBTA inspectors found no problems with the equipment.
On Friday, the T released a video from the station's stairwell that paints a partial picture of what happened, showing one trolley pulling up to the outbound platform at 11:48 a.m., lights flashing to indicate a stop, and opening its doors.
About 12 seconds later, after passengers had a chance to disembark or board, the front of the trolley bucks up from the tracks briefly and then lurches forward, stopping several feet ahead, doors still open. The location of the camera and an overhead sign in the station block the rear trolley — or the driver in question — from being seen in the video.
In the aftermath, one passenger can be seen tumbling out of the front trolley, standing briefly, and lying down on the concrete station floor, legs splayed, before crawling back inside. But some other passengers mill about, as if they had experienced a minor fender-bender.
The force caused the trolleys to link together, forming one long four-car train from a pair of two-car trains. They did not derail. The damage to the vehicles appeared to be minor, though the T did not yet have a dollar estimate, said Joe Pesaturo, spokesman for the Massachusetts Bay Transportation Authority. The ongoing investigation indicates that the rear train was moving about 10 to 13 miles an hour when it struck the front train, he said.
The driver of the front train, a 24-year-veteran, remained hospitalized Friday as a precaution, Davis said.
The driver under investigation will be interviewed again, and officials expect to conclude their review and share findings with the public next week, Davis said, stressing that the Green Line is safe.
The T initially identified the driver as a 46-year-old hired in 2006, with no accidents on his record. Pesaturo clarified Friday that the man was cited for speeding on the Green Line in July 2009, but had been accident-free since then.
The crash occurred less than a week before the state Transportation Board is scheduled to be briefed on a two-year, $2 million study of whether to equip the Green Line with a safety system known as Positive Train Control, an automated feature that can force a trolley or train to slow down to avoid a collision.
The federal government has mandated Positive Train Control on commuter rail by 2015, but it is not required for light rail such as the Green Line. But the National Transportation Safety Board urged the T to consider Positive Train Control after a 2008 crash in Newton that killed a Green Line operator who apparently experienced what investigators termed a "microsleep" episode while driving.
The T declined to provide details on the Positive Train Control analysis, but preliminary findings from the national infrastructure firm HNTB Corp. published in the company magazine indicate that it could cost $12 million to $20 million a mile, or $500 million to $1 billion for the 46 miles of track along the Green Line.
The Green Line is the nation's highest-capacity light-rail system, moving 250,000 riders on busy weekdays, and it poses unique engineering challenges, with narrow underground tunnels and tight curves that date to 1897.