BART strike

Striking BART workers picket in front of the Lake Merritt station on Monday. (Justin Sullivan / Getty Images / October 21, 2013)

WALNUT CREEK, Calif. -- A  federal investigator in charge of probing Saturday’s fatal BART accident said a trainee was operating a  train when it struck and killed two workers who were inspecting the tracks.

James Southworth, who is in charge of investigating the accident for the National Transportation Safety Board, said the driver/operator was one of two trainees on board with a management trainer when the accident occurred. Three others on the train had mechanical duties, he said.

BART has indicated it was exploring the possibility of using managers to run the trains in case the strike is prolonged. Southworth said the train’s mission Saturday was both training and maintenance.

He said the trainee operator, whom the NTSB interviewed Monday, had sounded the air horn before the accident. The train was moving at 60 mph to 70 mph when it made an emergency stop, Southworth said. He said the operator had heard a radio report warning of workers on the track.

“He was aware of people on the tracks,” Southworth said.

Southworth said video inside the cab of the train has been sent to NTSB headquarters in Washington for analysis.  He said investigators interviewed four employees Monday, including the train operator, and individuals involved in dispatch and track inspection. Southworth would not identify the individuals by name.

He likened the NTSB investigation to a “well-orchestrated industrial ballet.” He said a final report on the cause of the accident could take six months to more than a year.

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Twitter: @mauradolan

maura.dolan@latimes.com