Reductions in the number of Metrorail cars are producing inevitable results throughout the subway system: Trains formerly known for comfortable standing or sitting room now often run at capacity load, bodies pressed against the doors.

The crowding began a month ago, after Metro cut some of the trains on the Ballston-Addision Road run from six to four cars and switched some Orange and Blue Line routing in an effort to save on operating costs, reduce chronic Blue Line delays and free up cars needed for the opening in December of three new stations along the Red Line.

In another economy measure, Metro last Saturday began operating two-car train on weekends rather than the usual four. In the late afternoon, rail operations chief Joe Sheard said, some of the trains were packed to capacity, leading riders at several downtown stations like Smithsonian to wait for following trains rather than squeeze their way aboard.

Overall, these changes have taken place: The size of weekend trains on all lines has been reduced 50 percent, from four to two cars apiece, except for special occasions; weekdays, on the New Carrollton-to-National Airport run there are 16 six-car trains rather than the former 13 six-car trains; and on the Ballston-to-Addison Road line, there are eight six-car trains and six four-car trains now rather than 14 six-car trains.

The average daily ridership on the Blue and Orange lines is 212,000, compared with 84,000 on the Red Line.

In a sense, what all of this means is that Metro is less and less a toy and increasingly a functioning commuter rail system like those in other cities. In the 1960s, the metrorail network was conceived as a futuristic showcase of American technology and design as much as a subway. Today, passengers find that their model system, must do battle with the same financial forces that have made crush loading and battered equipment standard fare in many of the country's subway systems.

Frances Hopkins, a GAO secretary who commutes downtown daily from her home in the Ballston neighborhood in Arlington, finds afternoon crowding on her trains discouraging. "I used to have nothing but praise for the system," she said before boarding a four-car train Tuesday morning. "But coming home is something else now." Inward service, she said, continues to be good.

Michael Jarboe, a supervisor at a downtown trade association, rides between the Court House and McPherson Square stations. Before the switchover, he rarely got a seat at rush hour but could count on boarding the first train to come. "Half the time now," he said, ". . . I will wait for a couple to go by." He likes at the least to have a bar to hang onto.

Metro officials say that before the Blue-Orange flip-flop, too many cars were assigned to the Ballston run in Arlington, creating small loads per car and empty space. Economical operation of any subway makes rush-hour crowding unavoidable, metro operations director Theodore Weigle said. He called the current Ballston density "acceptable" if not "desirable."

"What our good patrons on the Ballston line are experiencing now is precisely what the patrons on the Red Line from Silver Spring experience every morning," Weigle said. That Red Line segment is the most heavily used in the system.

In the morning at Ballston, the peak hour runs from 7:43 to 8:37, Weigle said. Formerly in rush hours, 10 trains of six cars each left in that period. Now six trains of six cars and four trains of four cars depart from the station, meaning eight of 60 cars have been cut from the run.

Weigle, who commutes by Metrorail, said he rides in from Ballston slightly before the peak, between 7:15 and 7:30, and has yet to encounter a crush load, which Metro defines a 229 passengers in a car (there are seats for 81). he encouraged commuters to try to use the subways during off-peak hours.

Not all passengers object to the reductions. Many rush-hour passengers, while aware that trains are smaller, don't see a problem. "It has no effect on me personally," said production coordinator Carolyn Miller while waiting for a train at Court House station. "I find it [subway service] very reliable, convenient, clean. They have delays, [but] so does my car."

And John Draper, a naval officer who rides the subway between Ballston and his job at the Pentagon, said he had seen a four-car train only once. The changes have had no effect on his commuting convenience, he said.

Brochures on the Blue-Orange realignment distributed by Metro cast it as a measure to improve efficiency, suggesting better service would follow. Metro officials say it did reduce delays that had plagued Blue Line trains. But it also increased crowding.

Weigle said that while restoration of more cars on the Ballston run is not foreseen, Metro planners are reviewing schedules for connecting buses, to try to accomodate transfer passengers arriving under the new arrangements.

Last week, Metro disclosed that the realignment was also part of a program to reduce rail operating costs by about $600,000 in the current fiscal year, as the Metro Board ordered when the annual budget was approved. Fewer cars means lower electricity bills and fewer repairs.

Like transit systems around the country, Metro is trying to cut costs. Reports for the last fiscal year show that economy measures had reduced the subsidies that the authority gets from the eight member jurisdictions by about $5.5 million from the budgeted level.