A key indictor of transit railcar reliability is Mean Distance Between Failures (MBDF), and by this measure the car fleet of MTA NewYork City Transit has made solid progress in the last decade.
In a statement Wednesday, the agency said that while spot problems continue, "it should be noted that the entire fleet's Mean Distance Between Failures (MDBF) 12-month average now stands at nearly 140,000 miles, compared to less than 90,000 miles in 1999. The improvement is due in part to the new R160 subway cars, which are now replacing the oldest cars in the fleet, and in part to enhanced maintenance of the existing fleet. Our passenger surveys show marked improvement in customer satisfaction on lines where these new cars have been deployed."
MTA was responding to a report of poor car reliability on the system's C line. Acknowledging that this line is still waiting for an older fleet of cars to be replaced, the agency cited improvement in the performance of the subway fleet as a whole, which numbers around 6,500 cars.