San Francisco Chronicle

Footage shows giant spark, not fire, officials say

- By Michael Cabanatuan Michael Cabanatuan is a San Francisco Chronicle staff writer. Twitter: @ctuan E-mail: mcabanatua­n@sfchronicl­e.com

BART officials, after reviewing surveillan­ce video, are sticking with their story that no fire was involved in the Sept. 16 incident that filled Civic Center Station with smoke and forced the station to be evacuated.

A preliminar­y investigat­ion found that the incident was a large electrical arc, essentiall­y a giant spark, they said Tuesday. It caused a bright flash of orange that shot up the side of the train and over its roof, produced loud noises and generated huge clouds of smoke.

The arc was likely produced when a piece of metallic debris caused a short circuit, said Don Allen, BART’s chief engineer. But witnesses described seeing a wall of flames. “This was not a fire in the sense of flames burning any solid material or causing any structural damage, but the bright flash of the arc has a fiery appearance,” he said. “There was a cloud of heavy smoke, so it is understand­able that to some passengers it seemed like fire.”

BART officials released surveillan­ce video from two cameras on the station platform and two on the concourse. One camera shows a train pulling into the station, heading toward the East Bay, when there’s a bright flash that looks like a fireball from the rear. On the other side of the platform, the video shows passengers moving away from the train as an orange burst of light illuminate­s the platform. One, holding a bike, appears to fall or be knocked to the platform, colliding with another passenger.

Allen said investigat­ors did not find any debris on the tracks but found some drops of molten metal. He said the arcing is similar to the torch used in welding, which uses 30 volts of electricit­y to produce a hot, bright arc across a ¼-inch gap. BART is powered by 1,000 volts of electricit­y, and the arc produced was likely over a 12- to 14-inch gap — the distance between the electric third rail and the nearest rail carrying the train.

“It’s like welding but powered by a much more powerful source,” he said.

BART plans to share the informatio­n with Muni, which shares the station, and with the state Public Utilities Commission, which oversees rail transit safety. Andrew Kotch, a commission spokesman, said the agency is conducting its own review and is expected to discuss the incident Thursday.

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