BART crews will be working through Memorial Day weekend to re-establish service lost after explosions and fire caused damage to the San Leandro station, officials said Thursday.
BART deputy general manager Michael Jones said they hope full service will be restored on the Green Line – which runs between Daly City and Berryessa stations -- by next Tuesday. The system was largely restored elsewhere during the day of the fire, but the Green Line has remained out of service.
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WATCH HEREBART officials also provided key details leading up to the meltdown of the system on Tuesday as well as an earlier network failure on May 9.
The latest failure involved the system that delivers power to the trains.
PG&E provides 100,000 volts of current to BART’s network. BART takes that power and reduces the load to 34,500 volts into a cable to its stations. At its traction power stations, the load is reduced further to 1,000 volts of direct current to power the third rail for the trains.
That’s where the problem began about 4:50 a.m. Tuesday, when an unexplained fault caused arcing on the line that feeds the third rail at San Leandro, officials said.
An aging circuit breaker – designed to stop the flow of excess power to protect the system – failed to activate in response to the surge.
As a result, the overflow in power led to explosions and the ensuing fire. Worse, there was a delay in emergency response because fire crews waited for BART’s assurance that power had been shut down.
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SIGN UP The fire damaged one of two 34,500-volt power cables that feed the system, authorities said. The cable, which is five decades old, had yet to be replaced as part of a system-wide upgrade. The board voted unanimously Thursday to authorize up to $8 million to repair the damaged power cable.
“While faults are not uncommon in the BART system, it is very rare that this fault escalated to this level,” BART said in an update posted on its website. “Typically, electrical faults are isolated by protections such as transfer trips and circuit breakers.”
BART officials said the network failure was the result of a “computer topography problem.” Operators at the Lake Merritt control center did not have confidence in the data coming from the computer system that controls track switching operations. The loss of confidence came after the flow of track monitoring data became intermittent, due to the simultaneous failures of two separate network devices.
