The Metro Transit Authority yesterday delayed for two weeks a major realignment of bus routes to feed the expanded Metro subway system because the subway is not working reliably enough to handle the extra crowds.

The decision was adopted unanimously by the Metro board on the recommendation of general manager Theodore Lutz. He told the board that during the two-week delay more automatic fare-collecting equipment could be installed at key subway stations and that the number of subway cars could be increased.

Balky trains running at irregular intervals and overworked fare-collecting equipment have plagued the Metro system in the two weeks since its new Blue Line opened from National Airport to RFK Stadium.

It had been Metro's intention to eliminate much parallel bus and rail service on Monday by rescheduling 210 bus routes.Many of the buses that now come downtown would be stopped at outlying Metro stations - particularly at Rosslyn and Stadium-Armory. Yesterday's board action means that that will not happen until Aug. 1.

The routes affected primarily serve riders living in North Arlington and western Fairfax County, southern Prince George's County and Southeast Washington.

Metro officials worried that the crush of bus commuters would overwhelm the fare-collecting system, which requires each subway rider to insert a magnetically encoded ticket in a turnstile both while entering and leaving the subway.

Furthermore, they worried that the minor but annoying mechanical problems that have pestered the trains themselves would be exacerbated under the pressure of thousands of more rush-hour riders.

"I think it is important to consider the adverse ridership and revenue impact if we "turn-off" potential and actual public transportation users at this point," Lutz told the board in a written memorandum.

Despite Metro's early troubles, riders have not been "turned off" so far. Lutz said yesterday that Metro is averaging 105,000 trips per day since the Blue Line opened July 1. That represents an increase of more than 60,000 trips a day over the old Red Line alone. It is, of course, too early to determine if that 105,000 represents steady users or merely curiosity seekers and joy-riders who will not come back to Metro.

Metro and other new subway projects are often attacked because of their similarity to San Francisco's Bay Area Rapid Transit (BART), which has not met its ridership projections since opening in 1972.BART, on a 70-mile system, is getting about 140,000 trips per day. Metro's 105,000 trips are on a 17-mile system.

Lutz told board members yesterday that he had found a way to pay for a two-week delay in bus cutbacks that would not require additional subsidies from area jurisdictions. Such subsidies come chiefly from local property taxes.

Lutz estimated that the cost of running the parallel bus schedule for two weeks would be $80,000 to $100,000 and said it could be reimbursed from a contingency account in the bus budget.

Revenue lost to the subway because riders complete their trips on the bus will total $125,000 to $150,000, he said. That can be covered, he estimated, by income from rail advertising that was not included in the current Metro budget.

There will be no delay in the Sept. 4 bus cutbacks, which affect primarily Shirley Highway corridor routes that cross the 14th Street Bridge, Lutz said. Then, many buses will be stopped at the Pentagon.

During the two-week delay, Lutz said, more exit gates would be installed at Farragut West, where there is a crush of people during the morning rush hours, and additional fare equipment will be placed at Rhode Island Avenue, National Airport, and Potomac Avenue.

The fare equipment is sold to Metro and maintained by Cubic Western Corp., which has constructed similar equipment for BART and simpler equipment for a rapid transit line between Philadelphia and the New Jersey suburbs. Both BART and Philadelphia officials told a reporter that they are happy with their equipment - but that they had start up problems with it.

"We are spending 8.6 per cent of revenues to collect revenues, and the industry average is 25 per cent," said the Philadelphia manager, Bob Johnson. "I know our equipment to be highly reliable."

Thomas Tuttle, Cubic's program manager of Metro, said yesterday that the biggest problem was that "there is not enough equipment, and that has been compounded by huge ridership."

Tuttle, and Metro officials as well, urged riders to buy high-value Farecards - the magnetic tickets - and thus reduce the number of times each rider would have to stand in line.

Pre-encoded Farecards worth $8 (20 rides at 40 cents) are available at a number of area banks and Metrobus ticket and token outlets.

The other problem - reliable subway cars - is improving. Metro was running 84 cars yesterday and would like to have 106 before the bus changeover. There were two delays in the morning that meant 17-minute waits for trains instead of the 10-minute interval Metro wants, but on the whole the day went as smoothly as any since July 1, train officials said.

By the time the bus changeover occurs, Metro wants a six-minute interval between trains on the Blue Line during rush hours.