New cars delayed, but BART says future fleet is still on...

BART’s highly anticipated introduction of new train cars was hit by a five-month delay, but officials said Tuesday that customers should still expect to be riding a full new fleet within five years.

The transit agency plans to press 10 new test cars into service by the end of the year as part of a pilot program in which it is running and studying the cars and trying to fix problems.

The five-month delay was caused primarily by the need for extensive wiring modifications in the cars, BART officials said. They said the new trains also continue to experience troubles with the reliability of equipment that powers lights, air conditioning, heating and part of a braking system.

These issues, among others, will need to be fixed before more cars can roll off the assembly line.

The problems, which BART has been aware of for more than a year, mean that the agency won’t receive the first new railcars until at least May, officials said. They insist the problems should have only a temporary impact on the arrival of 775 new cars BART has ordered from Bombardier, a Canadian railcar manufacturer.

“We’re still on track to meeting the schedule of when those cars go into service,” said Alicia Trost, a BART spokeswoman.

The schedule calls for BART to have 60 new cars by the end of 2017, 230 by 2018, 420 by 2019, 610 by 2020 and all 775 by 2021.

BART is counting on the delivery of the new railcars to help relieve the overcrowding, breakdowns and service delays that have increasingly plagued the system over the past few years as the agency has been simultaneously hit with aging equipment and surging ridership.

The first of the pilot cars arrived in March, about three months behind schedule, and was put into testing at BART’s Hayward maintenance yard. Another three have arrived since, and six more are expected by the end of the year.

BART’s contract with Bombardier calls for the manufacturer to deliver 10 cars that will be tested for a year to discover — and fix — problems before it cranks up the production line at its assembly plant in Plattsburgh, N.Y.

The biggest problem that BART is dealing with involves the auxiliary power system, which provides electricity for tasks other than propelling the train. That includes lighting, air conditioning and heating as well as pumping hydraulic fluid to one of the braking systems used to slow and stop trains.

The power system failed what BART called longevity testing — intense shaking and vibrations — that showed it would not last 30 years as designed. BART engineers also found that the system tended to shut down when it reached 300 degrees, said agency spokesman Taylor Huckaby, and that it shut down when maintenance workers plugged in multiple floor cleaning machines.

“This is stress testing,” he said. “We’re trying to break the test train in essence.”

BART was aware of problems with the power system, Trost said, but agreed to accept the 10 test cars anyway so they could inspect other parts and not slow the arrival of the new cars more than necessary. BART engineers are working with Mitsubishi, the manufacturer of the power system, to resolve the problems and expect they’ll be rectified.

“We don’t have any concerns at this time,” Trost said. “There’s no reason to believe we won’t fix the problem.”

While it will start late, Bombardier has agreed to step up production to meet BART’s needs for new cars, which will increase when the Warm Springs extension in Fremont opens this fall and the Berryessa extension to San Jose joins the system by 2018.

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan