"This is work that we've delayed and tried to get done in the overnight hours," he said. "We're just not able to delay it any more. We need to really get in there, tear it apart and rebuild it, and the only way to do that is to disrupt the lives of a lot of people."
SamTrans and Muni are providing free buses between the closed stations. BART projects the ride will take 15-20 minutes but is advising commuters to the airport to either budget an extra hour of transit or make other arrangements.
A commuter to the airport from downtown San Francisco on an impacted weekend would need to take four legs of travel to get to a domestic terminal.
Data provided by BART show that on average, the corridor ridership is 23,000 people on a typical Saturday and 18,000 on a typical Sunday. In an emailed statement, Allison wrote that the system has seen a 50 to 60 percent decrease in ridership during previous weekend closures, so BART is expecting to transport 9,000 to 15,000 people each weekend by bus during the upcoming closure weekends.
BART's aiming to replace a half-mile interlocking section of rail that allows trains to switch tracks. Allison says these interlocking sections are crucial for maneuverability during delays in the system.
“A lot of the components have reached the useful end of their lives, so we need to tear it apart and rebuild it," he said. "It is pretty complex in terms of rail structure. That’s why it’s time-consuming and labor-intensive.”
This is also one of the noisiest sections in the system. Rail corrugation plus a curve in an elevated track makes for a screechy commute on the stretch of track connecting San Francisco to the Peninsula. BART crews will install rubber and steel noise dampeners near Balboa Park over Labor Day.
Allison says the sound dampening upgrade costs about $1 million per mile.
More to Come
Weekend closures are a “new reality” for BART, Allison said. Built in the 1960s, the system is entering an era where equipment needs to be replaced, rather than patched up.
“This is not the first weekend shutdown that we’ve had," he said, "and it won’t be the last.”