The Metro subway's automated fare-collecting machines are supposed to count subway riders in addition to taking their money, but the best that the Farecard system could do Monday was estimate that trains carried between 110,000 and 130,000 people.

On Monday, Metro changed or eliminated 210 bus routes so buses would feed the subway system rather than compete with it. Metro had estimated that an average of about 30,000 people would be forced from buses and onto trains.

Because of the inexactitude of Fare-card's estimate, Metro does not know how well the rain system performed Monday, although Metro probably had its heaviest day of subway ridership since the Blue Line opened July 1. In the week of July 25-29, Farecard totals showed that subway ridership averaged between 1000,000 and 110,000 persons each day.

"Each exit gate has a tape in it that tells us how many people left the trains," Metro spokesman Cody Pfanstiehl said. "But the tapes are hard to read, and we have not been able to get exact ridership information. It will get better."

August is a difficult time of the year to study transportation trends because much of Washington is on vacation. Attendance at federal offices was reported down Monday.

In other Metro developments, three major train breakdowns occurred during rush-hour periods yesterday, and some riders managed to be involved in two of them.

During the morning rush hour, "We were perfect until 8:37 a.m.," supervisior Arthur Seeger said. "I mean, every train was dispatched within a minute of the right time."

But at 8:37, a.m., a train headed toward Arlington Cemetery and Rosslyn automatically came to a halt because of an overloaded brake warning.

The operator inspected the train and determined that the warning was faulty, not the brakes. He then disengaged the brake warning and took the passengers to Rosslyn, where the train was unloaded.

During this time-consuming process, two trains were sent in each direction around the stricken train on the opposite track. The first Washington-bound train through the Rosslyn station picked up most of the passengers who had been taken from the disabled train.

The heavily-loaded train bound for Washington limped "very slowly." Seeger said, under the Potomac River and into Washington, before refusing to move after reaching the McPherson Square station. After a 9-minute delay, the operator restarted the train.

The two incidents meant a general breakdown on the Blue Line. There was a 30-minute gap between trains from the Stadium to National Airport before the situation was cleared.

In the evening rush, a train stalled in the crossover at the Eastern Market station, where all Blue Line trains normally are turned around. For about an hour, passengers were transferred from Capitol Hill Metro stations to Metrobuses and carried to the Stadium Armory station at the end of the line. Normal subway service was maintained on the rest of the Blue Line by turning other trains before Eastern Market.

Also yesterday, George Davis, president of the Amalgamated Transit Union Local 689, which represents train operators, said he was filing a greivance with Metro because an operator had been suspended for five days after a July 15 incident.

Metro had confirmed Monday that a riderless train was driven through a red stop signal and onto another track. Davis said the operator, who normally works only in the yard, had been ordered to take the train on an unfamiliar route when the incident occured.

Anthony J. Stefanac, Metro's rail superintendent, said any operator should be able to operate anywhere on the system by following signals. Stefanac confirmed Davis' statement that after the July 15 incident special familiarization training on the switching area where the incidient occurred was given all Metro train operators who normally work in the yard.