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Tuesday, September 25, 2012

BART Evacuation Caused by Crazy Bright Arc of Electricity

Posted By on Tue, Sep 25, 2012 at 4:34 PM

click to enlarge In case you weren't on the train that day ...
  • In case you weren't on the train that day ...

BART has completed its investigation into the bizarre smoke-filled evacuation at Civic Center station a week ago, blaming the incident on a random 1,000-volt arc of electricity.

According to the agency's preliminary report, the arcing was adjacent to a train entering the Civic Center station, which created "smoky conditions" and forced passengers from the train. The BART Safety Department concluded that the arc was most likely caused when the train struck trackside debris that conducted electricity.

The 1,000-volt arc sparked a "bright flash of light, loud sounds, and smoke" for no more than 30 seconds. It scared the hell out of passengers, but didn't cause any major damage to BART trains or equipment. However, there have been two reported

complaints of smoke inhalation, the agency said.

For you English majors, an electric arc is a discharge

of current, which can be short-lived but really bright, that occurs when a strong current

jumps across a gap in a circuit. That's the best way BART could describe it. 

"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," said Chief Engineer

Don Allen. "There was a cloud of heavy smoke so it is understandable

that to some passengers it seemed like fire."

According to BART:

The 1000 volts of electricity used to power BART trains is supplied through an electrified third rail that is supported at 10-foot intervals by porcelain

insulators. A collector shoe extending from the bottom of the train car

contacts the third rail, completing the electrical circuit. If there is a

gap in this circuit for any reason, the electrical current can arc to

ground. Arcs similar to those of Sept. 16 have occurred before on BART

but are a relatively infrequent occurrence.  Minor arcing between the

car collector shoe and the third rail has been observed on BART trains

operating outdoors at night.

"The safety of our passengers is our top priority. We apologize for the inconvenience and for those passengers who were startled by the arc and

smoke," said BART General Manager Grace Crunican. "All our front line personnel undergo extensive training and we

conduct regular inspections to make sure our equipment meets safety


Now here's what you can do to help prevent this kind of freak accident from happening again: Keep the BART tracks free of debris. That means, don't bring your food or trash onto the stations.

Also, please read the "guide to emergency procedures" that's posted on each train car on your commute home tonight.

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About The Author

Erin Sherbert

Erin Sherbert

Erin Sherbert was the Online News Editor for SF Weekly from 2010 to 2015. She's a Texas native and has a closet full of cowboy boots to prove it.


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