Bowing to citizen pressure, the Fairfax Board of Supervisors has agreed to start Saturday service for Metrobus Route 26A, but at the same time it announced plans to cancel night service on the cross-county route.

To cover the cost of the Saturday service, the board decided that weekday hours on the route would end at 7 p.m. instead of 11 p.m., county transportation spokesman Andrew Szakos said. The shorter hours would save an estimated $10,000 a year, he said.

The supervisors have authority to increase service. But before the night service can be cut, Metro must hold a hearing, which probably will be scheduled later this fall. After the hearing, the county board, which buys its bus service from Metro, has the authority to make a final decision on the cut.

Szakos said if there is widespread opposition to cutting night service, the board may cancel its plans for Saturday service.

"I would say one is contingent on the other," he said. "If a lot of people turn out at the public hearing or if the Saturday ridership is low, we'll have to go back to the board."

The county is planning to start the Saturday service in January, when most bus route changes are made. The service would be on a six-month trial basis, Szakos said.

More than 500 Fairfax residents petitioned the supervisors for the Saturday service on Route 26A, which crosses the county along Backlick and Gallows roads. The transportation staff had recommended the board turn the proposal down as too costly.

"It pays to organize," said Mary Sue Lyons, a leader of the drive for the weekend service.