The Embarcadero BART station is getting a thorough scrub-down this week. Workers on the graveyard shift have been sandblasting sections of the walls along the tracks at night, says BART spokeswoman Alicia Trost.
The results are dramatic: It almost appears the clean sections of the wall have been painted white.
Despite appearances, the station walls aren't plain gray concrete but are actually white terrazzo, a composite material made of rock and glass chips suspended in cement. Decades of brake dust from BART and Muni trains, plus the grime brought into the stations by humans, have caked the walls in filth.
“The main reason that Embarcadero is such a problem station with the walls getting as dark as they do is that it’s the first station out of the Transbay Tube," Trost said. "The walls collect all the subway grime and train brake dust that blows out from the tube."
Earlier this year, a decades-old textile installation, "Legs" by Barbara Shawcroft, was removed from the station. Originally orange, the work had grown so dark with soot it was barely perceptible against the station walls. In its 35 years on display, it was cleaned twice, at great expense.