Fairfax County and Vienna officials are hoping an experimental "jitney" bus service from Oakton to Tysons Corner will pick up enough ridership to justify its continuation.

Begun in August as a one-year pilot program with $140,000 from county and state funds, the jitney bus has not yet lived up to expectations, said Chris Jenks, an associate transportation planner for the county. (A jitney is a small vehicle that transports passengers for a low fare; it usually runs a fixed route, but not necessarily on fixed times, as it waits for a full passenger load.)

The service has two 18-passenger buses leaving every 30 minutes at alternate ends of the route, which begins at Germantown Road in Oakton. The buses run through southern Vienna to Tysons and back. The fare is 50 cents a person; children under 5 ride free if accompanied by an adult. The buses, operated by Assist Inc., run six days a week, from 6:15 a.m. to 6:45 p.m. on weekdays and 9:45 a.m. to 6:45 p.m. on Saturdays.

Marie Kisner, Vienna's public information director, said the purpose of the service was to reduce traffic along Rte. 123 (Maple Avenue), the main street in Vienna, provide local transportation for carless people -- particularly the elderly -- and to reduce noise and air pollution.

"It's just a local little bus service," Kisner said. "You flag the buses down like they were taxicabs because there are no fixed stops."

There hasn't been much flagging, although the service has been very popular with those who do use it, Kisner said. She noted that on a "free-ride day," when the Chamber of Commerce picked up the tab, 652 people rode the buses, compared with 715 the entire week before. Another free-ride day, sponsored by the Rotary Club, is set for Dec. 13.

Before the service began, county transportation officials established three criteria for determining its success: a 10.4 percent return from fares; an average of 10 passengers per trip, and a maximum subsidy of $2.29 per passenger.

But, the county's Jenks said, in September the average subsidy was $3.35 and the average passenger load was 4.5 persons. The 10.4 percent return from fares was based on a 25-cent fare, but since the fare was doubled to 50 cents, the return should be nearly 20 percent. Instead, Jenks said, the actual return is 14 percent.

"[The operation is running at half stream right now, but steadily and slowly, as word gets around, it's picking up ridership," Kisner said.] "I think the main problems are the routes the buses take and the fares, especially when you consider that some people might want to make multiple stops and would have to pay 50 cents each time they got on."

For elderly persons who want to go from Vienna to Tysons Corners, she said, the fare would actually be cheaper (30 cents) on a Metrobus because of senior-citizen discounts.

The problem with the route is that the buses go through southern Vienna only and do not run the full length of Rte. 123, since the buses returning from Tysons wind through residential areas.

Town officials are hoping the county will agree to reduce the fare for elderly riders and improve the route when the system is reviewed in January, Kisner said. Many town residents also have requested expanded service and an arrangement that would permit transfers from jitneybuses to Metrobuses.

"For the most part, a service like this is not particularly profitable," Jenks said, noting that similar private operations have been tried twice before without success. "But we'd like to give it a little bit more time."