Serenity Now! BART Finds a Solution to Its Screeching Trains
Aarian Marshall writes: "Some 44 years after BART opened, the transit agency has finally figured out how to tamp down the racket, and make life just a bit nicer for its 420,000 daily weekday riders: It’s shaving its metal wheels by two millimeters."
The solution followed research across four years, three contractors, and a year of testing according to Marshall, but the implementation is expected to be simple compared to some of the other big projects underway on the system.
Marshall also explains in more detail what made BART trains so noisy:
Turns out, it’s all about shape. The current round BART wheels sit on a fixed axle, so they don’t spin independently of one another. When the train turns, the outside wheels want to go faster than their inside counterparts, which get dragged along. This inside “slipping” not only makes extra noise—it warps the rails. Called “corrugation,” that damage makes the the [sic] goshdarn hubbub even worse.
In response, new BART wheels will be slightly tapered. Voila! Serenity.
Another benefit of the wheels that have been engineered to solve the problem: "BART expects the new shape to increase a wheel’s lifespan from three years to seven."