Metro began Sunday subway service yesterday with trains running smoothly and carrying up to twice as many passengers as had been expected.

Officials of the transit authority estimated between 75,000 and 90,000 trips were made on the two rail routes as hordes of tourists and area residents descended on the Mall and thousands of football fans converged on Robert F. Kennedy Stadium for the Redskins' opening game.

Metro officials said yesterday's patronage far exceeded the 50,000 or so that had been expected. Planners had forecast 35,000 trips on a typical Sunday, with still more riding whenever the Redskins play here. The team has six more Sunday home games this season.

Even the first trains on the lines at 10 a.m. yesterday carried sizable numbers of people, almost all clad in casual clothes and obviously bound for recreational outings. "You've got a lot of visitors depending on this system," said John Wood of Birmingham, Ala., who scanned the Metro map at the Rosslyn station with a friend, Kathy Frieling.

Most early riders got off at Smithsonian station, which has an exit in the middle of the Mall. Within an hour after service began, there was standing room only on trains en route to the Stadium-Armory station.

The parking lot at New Carrollton station was nearly filled with cars of football fans who fringe-parked free and took trains the rest of the way.

It took about an hour and 20 minutes to load all the transit-riding football fans who left the stadium after the Redskins' 29-27 loss to the Houston oilers. The crowds, which were orderly, were kept lined up more than 20 abreast at the tops of the escalators and allowed to enter the station gradually to avoid overcrowding of platforms and trains.

"We didn't mind. It was a nice afternoon and we sat on the lawn (outside the stadium) waiting for the crowd to disperse," said Marjory O'Leair, of Silver Spring, who attended the game with her daughter, Susan. "We were in no hurry to go anywhere."

Nicholas J. Roll, Metro's assistant general manager for transit services, who personally directed operations at Stadium-Armory, estimated that 17,000 to 20,000 boarded trains there after the game. If all rode Metro both ways, that would mean 34,000 to 40,000 trips.

Metro will not have its actual Farecard gate count until tomorrow, Roll said.

Members of the Metro board warned several months ago, when the decision was made to start Sunday service, that it might be discontinued if it is not well used.

Even with patronage at higher levels than forecast, the service will continue to run at a financial loss, Metro officials said. The deficit for the first year of Sunday operations is budgeted at $800,000, which must be made up by contributions raised from taxes by area governments.

Joanne Steller, public relations director of Woodward & Lothrop, said the number of customers who entered its flagship downtown store for the first Sunday opening in about a decade was "better than we expected. Traffic patterns looked to the store managers like a regular weekday."

Sales were 30 percent better than expected, she said. About 140 people were waiting when the store opened at noon, many at the door that leads directly from the Metro Center subway station.

As a special promotion, Woodies promised customers who made minimum purchases a free 50-cent Farecard for the trip home. The store had about 650 on hand but ran out of them by mid-afternoon, she said. In the end, the store gave 50 cents each to another 360 customers in lieu of farecards, Steller said.

Most smaller stores in the downtown area were shuttered yesterday, with their managers taking a wait-and-see attitude.

Metro marked the start of Sunday service with a brief ceremony held when the first trains arrived Sunday morning at Metro Center Station on both lines. Two pioneer Metro officials -- Warren D. Quenstedt, former deputy general manager, and Carlton R. Sickles, a longtime member of the board of directors, now retired, were on hand for the event.

The congregations from six churches that are clustered around Metro Center held a joint service in the station welcoming the Sunday operation, with their ministers voicing hope that it will encourage more attendance at regular services.

The service was held on a mezzanine level in the station, which the Rev. George Hill of Calvary Baptist Church described as "this underground cathedral," indicating its vaulted concrete roof.

Seeking a tongue-in-cheek biblical reference, Hill told 300 spectators that he thought of the Queen of Sheba who "came to Jerusalem with a very great train."

For the service, the Rev. William Moreman of the First Congregational Church composed this special litany:

"Enjoying the city is a way of rebuilding it. Now, on Sundays, the city becomes more open for enjoyment. We celebrate that!

"A city is a body with many systems needed for its health. This is the circulatory system, the flow of people's energy in the city. We celebrate that!"

Other congregations sponsoring the service were the Episcopal Church of the Epiphany, Metropolitan Community Church, Mount Vernon Place United Methodist Church and New York Avenue Presbyterian Church.

Also participating was D.C. City Council member Jerry A. Moore, who is both the pastor of the 19th Street Baptist Church and chairman of the Metro board. "The prophets of the past have seen the fulfillment of this dream," he said.

Trains will be operated again today, Labor Day, on the same schedule with service at 10-minute intervals from 10 a.m. to 6 p.m. That will be the schedule for future Sundays and holidays.

The fare for Sunday travel is the regular offpeak subway fare of 50 cents regardless of the length of the trip, with transfers provided from trains to buses but not from buses to trains. Senior citizens who buy special Farecards are charged fares that depend on the length of the trip, ranging between 25 and 50 cents.