Imagine owning 5,803 cars - some of them 35 years old. Let's say that together they drive 300 million miles a year. Now imagine keeping that tremendous fleet of vehicles in top running order.
That's precisely what the New York City Transit has to do with its subway cars. In charge of ferrying 3.6 million customers a day below the streets of New York, the transit authority can't afford unexpected breakdowns.
To avoid having to pull a damaged car off the tracks and send a replacement, the transit authority has designed an intricate matrix of scheduled checkups and part replacement - similar to oil checks drivers make for their cars, but on a grander scale.
Every six years, each train car makes a stop of several days at one of two repair shops. During that time, the car is completely overhauled - motors and air brakes are replaced, a fresh coat of paint is applied, new wheel bearings are secured. In between, cars go for frequent checkups at smaller shops.
Because the subway system is so complex, supervisors know a year in advance which cars they will be servicing. That way, they have needed parts on hand when the cars come in, says Frank Silecchia, general supervisor of the Coney Island Overhaul Shop.
Another secret to keeping the train cars running: Mechanics can look at the cars' repair histories. Each car has a team of the same three mechanics. In addition, computers can search out the car's past failures, what its defects were, and how they were treated.
The transit authority didn't always run such a tight ship. "We used to have cars wall to wall here," Mr. Silecchia says. "Years ago, we used to do so-called breakdown maintenance." That consisted of waiting for a car to fail, towing it to the shop, and having it sit there for sometimes as long as six months while the problem was diagnosed and parts were ordered.
In the late 1980s, the system was revamped. Researchers conducted computer analyses to determine how often cars needed attention, and a plan was drafted.
The results have been dramatic. A car breaks down every 52,400 miles now, versus every 7,200 miles before. New York's subway cars have a 5 percent failure rate today, Silecchia says. "That's well below industry standards."
The Coney Island shop is a mechanic's paradise. Workers labor in fluorescent-lit, underground bays. Bright yellow cranes built into the ceiling lift axles, heavy equipment, and the cars themselves, whisking them from one end of the cavernous station to another.
But quality could slip if the city starts skimping on its subway budget, Silecchia says. "Over the last four years, they've really tightened up on funds." Looking on the bright side, he says: "That gives the option to fail or come up with a cheaper way. I guess it just means that we've gotten better."