The Northern Virginia Transportation Commission agreed last night to reexamine the idea of providing commuter bus service from the Virginia suburbs to the District, while working to resolve problems stalling its commuter rail project.

The commission staff considered bus service in 1985, but chose instead to push for rail service along two corridors between Washington's Union Station and Manassas and Fredericksburg, Va.

Rail service could begin as soon as March 1989 if proponents can overcome several obstacles, including the problem of obtaining insurance and the opposition of one railroad to allowing commuter trains on its tracks. Commuter rail organizers envision running four rush-hour round trips a day carrying up to 4,000 commuters inbound each weekday morning, and the same number home each evening.

Greyhound/Trailways told the commission two weeks ago that it could serve the same number of people at lower cost by bus, and begin the service within 90 days after signing a contract.

"Given the need for immediate commuter relief in both corridors, I respectfully suggest that NVTC consider supporting luxury commuter bus service provided by Greyhound at least as a transition measure, but perhaps also as a permanent solution and alternative," said Theodore Knappen, senior vice president of Greyhound/Trailways, said in a letter to the commission.

Greyhound provides contract bus service from suburbs into downtown areas of Dallas and San Francisco, Knappen said.

Greyhound would use 100 buses to serve 4,000 riders a day at a cost of $10 million a year.

At the $7 round-trip fare proposed for commuter rails, the bus service would produce revenue of $7 million a year, Knappen said. The net annual operating subsidy cost would be $3 million, he said.

The buses would require no additional equipment and construction costs, while the commission estimates $40 million in start-up costs for commuter rail.

"Thus, even factoring in inflationary increases, bus service would be operated for roughly a decade for the capital cost of just starting up the rail service," Knappen said.

"For the next few years, while the rail service problems are being worked out" and planned extensions of HOV lanes (highway lanes reserved for vehicles with multiple passengers) "are being completed, luxury motor coach service is a very desirable alternative," Knappen said.

The commission voted to spend $25,000 in federal and local money to study the possibility of contracting for commuter bus service.

The commission also noted that in its 1985 study, the staff found that the costs of rail and bus service would be very close, but that rail ridership would be higher.

The commission staff also noted that buses would be mired in the same traffic that creates the need for rapid transit. Knappen estimated that the bus service would remove 2,500 cars from the road during rush-hour periods.