Metro will provide as much extra transit service as it can muster for Pope John Paul II's mass on the Mall Sunday, Oct. 7, but those attending should expect some confusion and difficulty, Metro General Manager Richard S. Page said yesterday.

Page's comments came after the Metro board gave him authority to extend subway hours and add bus service. "The board and the public should know that Metro is not going to be able to handle the crowd expecting to see the Pope," Page said. "I predict that thousands of people will walk long distances and that there will be massive confusion. We're going to do the best we can."

The crowd for the mass is predicted to range between 500,000 and 1 million people. The only comparable throng in Washington gathered on July 4, 1976, for the Bicentennial fireworks. Thousands of people who ride metrobuses to the Mall that night were stranded for hours in what is generally regarded as Metro's worst day ever.

Metro board members were clearly mindful of that night when they told Page yesterday "to provide sufficient service consistent with available resources."

One of the problems Page faces is that metro's bus drivers, subway operators and station attendants cannot be compelled under their labor contract to work overtime or to work on their days off, according to labor relations director William Leonard. Sunday is a day off for most Metro employes because the subway runs only eight hours and very few buses are on the streets. Volunteers from among Metro's regular drivers are being sought to work the day of the mass.

Metro tentatively plans to run the subway from 6 a.m. to midnight that Sunday and to run its buses on an augmented Saturday schedule. Under regular Saturday schedule, buses run twice as often as they do on Sunday.

Subway patrons will not have to fight Farecard, the automatic ticket-dispensing and fare-collecting system. Instead they will pay a flat 50-cent fare by tossing the exact change into barrels at the station entrances.

Page said he could not estimate the cost of the extra service because plans are not completed and it is unclear how many employes will volunteer to work.