As you likely heard or experienced last Friday if you're a commuter on BART, the beleaguered rail service had a new encounter with a year-old problem on tracks between North Concord and Pittsburg-Bay Point station, which caused systemwide delays for a number of hours. BART said on Saturday that the problem did appear related to the voltage-spiking that similarly took rail cars out of service last March and April and 22 cars were knocked out of service on Friday. Now, as the Chronicle explains, we're getting a better picture of what BART's multiple outside experts actually did figure out last year, and what the likely culprit was that led to Friday's troubles.
Signs point back to BART's efforts to reduce all that screeching noise on trains by running rail-grinding machines over sections of track. Track improvements like this were ongoing through 2015, and BART's hired experts last year determined that the metal particles left behind between the tracks had been getting stirred up by passing trains and were adhering to the bottoms of train cars.
Per the Chronicle:
The particles... were clinging to the undersides of rail cars, interacting with ground moisture and high levels of power to cause arcing, or electrical flashes. Since then, BART has used vacuum trucks to trail rail-grinding machines and suck up the particles inside tunnels. Engineers thought wind and rain [from winter storms] were washing away particles from rail grinding on ground-level tracks, sweeping them into the gravel ballast underneath. But that was apparently not the case between North Concord and Pittsburg/Bay Point, where crews have been grinding rails four nights a week for the past three and a half weeks.
BART spokesperson Jim Allison now says that they will be outfitting maintenance vehicles with powerful magnets that will pick up stray particles without picking up the gravel between the railroad ties, as the vacuums did.
Meanwhile, they think this was happening between North Concord and Pittsburg and not elsewhere in the system because the trains use more power when going uphill, as they do here. Thus, BART trains are using five percent less power in this area to try to reduce the risk of electrical arcing.
In the meantime, because of the newly damaged cars, BART is running some shorter trains in the system 568 are in service, short of the goal of 595 at all times.