OAKLAND, Calif. (AP) -- The commuter train that struck and killed two San Francisco Bay Area transit workers didn't have a front-facing video recorder, but interviews, inspections, audio recordings and camera footage from the train's cab should provide enough evidence to determine a cause, a federal investigator said Sunday.
Jim Southworth, the National Transportation Safety Board's railroad accident investigator-in-charge, confirmed that Saturday's accident involved a Bay Area Rapid Transit train that wasn't carrying any passengers because of the labor strike that has shut down the system since Friday.
But whether the work stoppage by members of the system's two largest unions or the way BART management deployed non-striking workers during the shutdown played a role in the fatalities will not be known for weeks or months, Southworth said.
"My concern coming out here, as it is for every investigation, is to find out what happened, to gather the facts," he said. "Whether the strike plays a role in that I can't say at this time."
BART officials said on Sunday that they could no longer discuss the accident because of the ongoing NTSB investigation.
BART's assistant general manager has said that the four-car train with several employees aboard was returning from a routine maintenance trip and was being run in automatic mode under computer control when it struck the workers who were inspecting a section of track in the East Bay city of Walnut Creek.
Neither BART nor the county coroner has released the names and ages of the victims -- one a BART employee and the other a contractor. They were the sixth and seventh workers to die on the job in the system's 41-year history.
Southworth said it is too early to know how fast the train was going or if workers saw or heard it coming. He and a colleague hope to interview the person who was operating the train and BART dispatchers as soon as Monday.
Even if the strike ended immediately, the ongoing investigation at the collision site means it would probably take a few days before trains could run on those specific tracks, he said.
"These accidents occur in an instant, but they take very long to investigate," he said.
On Sunday evening, transit workers, many of them dressed in their uniforms or union T-shirts, held a candlelight vigil for their colleagues.
"All over the system we are hurting because we are family here," Nucion Avent, a tearful BART worker, told the Los Angeles Times.
The NTSB has been promoting improved safety measures for track maintenance crews since the May death of a foreman who was killed by a passenger train in West Haven, Conn., spokesman Eric Weiss said.
In June, the board urged the Metro-North Railroad to provide backup protection for crews that were relying on dispatchers to close tracks while they are being worked on and to light the appropriate signals.
The investigators now in California will be checking to see if BART uses "shunts" -- a device that crews can attach to the rails in a work zone that gives approaching trains a stop signal -- or any other of the backup measures the NTSB recommended for the Metro-North system, Weiss said.
"Obviously, we are very concerned anytime anyone dies in transportation accidents, but we're very interested in the issue of track worker deaths right now," he said.
A 2007 report by the U.S. Bureau of Labor Statistics found that between 1993 and 2002 a total of 460 railroad workers died on the job, 132 of them were pedestrian workers struck by trains and other rail vehicles. Of all the accidents, 62 involved local passenger trains.
Although freight trains are required to have forward-facing cameras, there is no standard practice for subway trains, Weiss said.
Meanwhile, with no indication that the striking BART workers would be back on the job Monday, the region was preparing for another day of gridlock on freeways and bridges clogged with commuters who would ordinarily be traveling by train. BART, the nation's fifth-largest commuter rail system, has an average weekday ridership of 400,000.
BART spokeswoman Alicia Trost said Sunday that transit officials and labor leaders have been in contact over the weekend, but the two sides did not have any plans to return to the bargaining table.
BART presented what it called its last and final offer to its unions a week ago but is open to restarting the negotiations if that is what the federal mediator overseeing the process wants, Trost said. The system's directors plan to hold a special closed meeting on Monday, she said.
"The tragedy has redoubled everyone's commitment to a quick resolution so we can move forward in a spirit of cooperation to provide service to the Bay Area," she said.
Amalgamated Transit Union local president Antonette Bryant said over the weekend that she would take BART's final contract before members for a vote this week, but expects it will be rejected.
Cone reported from Fresno.
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