Another problem is the dearth of readily available replacement parts for BART's one-of-a-kind systems. Maintenance crews often scavenge parts from old, out-of-service cars to avoid lengthy waits for orders to come in; sometimes mechanics are forced to manufacture the equipment themselves. "Imagine a computer produced in 1972," says David Hardt. "No one is supporting that old equipment any longer, but those same microprocessors are what we have controlling our logic systems." Right now BART needs 100 thyristors at a total cost of $100,000. BART engineers said it could take 22 weeks to ship them to the San Francisco Bay Area to replace in BART’s "C" cars, which make up the older cars in the fleet. Right now, the agency has none. Nick Josefowitz says it makes no sense to dwell on design decisions made a half-century ago. "I think we need to use what we have today and build off that, rather than fantasize what could have been done in the past. The BART system was state of the art when it was built, and now it's technologically obsolete and coming to the end of its useful life."