Update, 10:30 a.m. Thursday: BART's offering more details of the Wednesday incident in which a train stopped abruptly in the Berkeley Hills Tunnel when a brake malfunctioned. Transit agency spokeswoman Alicia Trost says a short-circuit in an emergency brake on one train car caused the brake to deploy while the San Francisco-bound train was traveling 70 mph between the Orinda and Rockridge stations. An apparent cloud of brake dust in the tunnel immediately afterward led 11 people to be treated for breathing problems and other issues when the train reached Rockridge, in North Oakland. Nine of the 11 were hospitalized; none had life-threatening injuries.
Trost told KTVU the car involved in the incident is 40 years old and had undergone comprehensive maintenance in late October and in August.
She also told KTVU the brake problem isn't a new issue:
Trost said BART had problems in the past with their train cars' experiencing shorts in the brake systems. This year, there have been three similar incidents.
“It used to be a huge problem about a decade ago, but they did some fixes to the brake box and now it happens only very rarely, unfortunately today," Trost said.
The San Francisco Chronicle's Michael Cabanatuan offers this context for Wednesday's episode:
But the system's aging trains - with an average tenure of more than 33 years, with many older than 40 years - are the most common reason for delays.
A Chronicle analysis in 2012 of delays lasting 15 minutes or more found that troubles with trains were responsible for 25 percent of delays. Brake failures were a leading cause, along with problems with propulsion systems, automated train controls, doors and electrical systems.
"It's part of our investment needs," Trost said. And while the transit system has ordered a new fleet of rail cars and has plans for a new train-control system and rail-maintenance facility, it will need billions of dollars more for upkeep and modernization of the system.
The transit agency will probably ask voters, many of whom are growing increasingly frustrated by BART's plethora of problems, to approve new taxes or bonds to pay for those improvements.
Update, 1:10 p.m.: The latest tally on passengers hospitalized in this morning's brake dust (not smoke) incident: 11. That comes by way of the Bay Area News Group, which cites Oakland Fire Department Battalion Chief Melinda Drayton. None of those hospitalized in the incident suffered life-threatening injuries.