The Bay Area Rapid Transit System (BART) in San Francisco has been hit with serious electrical problems in the past few weeks. The issue that closed the Pittsburg-Bay Point station began March 16th when 50 cars were damaged after they were hit with a power spike as they moved through a track crossover north of the North Concord station. The surge shot up to 2,000 volts into the cars — twice what BART expects for normal operations — and caused a thyristor to fail in each car. BART said the parts cost $1,000 apiece and are difficult to acquire.
BART has 669 total train cars in its fleet and is supposed to be running 579 during a typical weekday commute, but on Friday was down to 521 cars. BART officials said Friday that they will be able to put many of the affected cars back in service within “several weeks” by temporarily taking eight to ten working cars offline and harvesting their thyristors. Some cars have five of the devices.
On Saturday March 18th they will run one test train car at 70 mph equipped with special measuring equipment.
A similar problem occurred in late February in West Oakland when voltage spikes near the Transbay Tube damaged some 80 cars. Most of those cars have been repaired, but some remain out of service. BART was able to “stabilize” the situation and keep cars from being knocked out of service, but was not able to figure out the root cause.
BART has newly built electrical substations near both the West Oakland and North Concord train stations, but BART spokeswoman Alicia Trost said engineers don’t believe the substations are to blame. When BART has shut down the substations, she said, the problem has persisted.
The problem has put a spotlight on BART's aging infrastructure, which is 45 years old. Kevin Heaslip, an associate professor of civil and environmental engineering at Virginia Tech said “preventative maintenance is not being done. It’s not things that happened today or yesterday — it’s years of being backlogged and behind on maintenance issues.”
Photo: Melanie Woodrow, ABC7newsBayArea
Propulsion for BART cars is provided by four 150-HP, air-cooled, electric traction motors – one per axle. Tractive energy is furnished via the third rail operating at 1,000 V DC. In brake mode, the cars regenerate energy to the third rail. Mechanical brakes operate via a hydraulic disc brake system operating on each axle and are automatically blended with the electric brake system. Each car is equipped with an auxiliary electrical system operating at 120/208 VAC, 60 Hz. Battery and battery chargers provide emergency power for lights, communication, and control equipment. Please send comments to:jharrison@aspencore.com.
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