An increasing number of commuters are using the new Herndon/Monroe park-and-ride lot in western Fairfax County, encouraging transportation officials who are hoping to turn more motorists into bus riders.

Nearly 300 commuters a day are parking their cars and riding the bus at the facility, up 32 percent from three weeks ago when 220 commuters used the lot daily, county officials said.

As a result, the number of motorists using the facility is now expected to balloon to more than 1,000 by next summer, as more people become aware of the lot and begin using it to commute to work, they said.

"It's getting pretty popular," said Young Ho Chang, the county's new transportation director. "We should see it filling up earlier than later."

The $30.4 million complex on the south side of the Dulles Toll Road, just west of the Fairfax County Parkway, opened with much fanfare late last month. It was designed to help relieve congestion along the Dulles Toll Road, one of the more heavily traveled highways in Virginia.

The facility allows commuters traveling from western Fairfax and eastern Loudoun to park their cars for free and ride one of 14 Fairfax Connector buses, including an express bus to Tysons Corner and West Falls Church Metro station. Bus fares range from 25 cents to $2. A Kiss-and-Ride lot and an area for carpoolers also are in the facility.

But the initial number of commuters using the park-and-ride lot was somewhat disappointing to officials as vast parts of the garage remained nearly empty. The complex has parking for 1,745 vehicles in addition to space for 80 car-pooling vans.

Officials said they expect higher usage of the lot as more people return from vacation. "It's the summer and frankly we didn't think we were going to have good counts until September or October after people start coming back from vacation," said Andy Szakos, chief of the county's transit operations, which overseas bus service and public transportation facilities.

Still, opening the facility in the summer, when traffic is historically low, has provided some help for transit officials who have been able to more easily work out bugs in operating the complex and scheduling the bus service.

Indeed, Szakos said that the county will make some bus scheduling changes next month that should improve some bus routes and make transfering from bus to bus easier.

For example, the 980 Herndon-Monroe Express bus, which takes riders directly to the West Falls Church Metro station and back without any stops in between, has been making the trip within 22 minutes, about 8 minutes faster than the schedule.

As a result, riders who needed to transfer to other buses had to wait the extra 8 minutes. Szakos said scheduling of connecting buses will be changed to reflect actual trip times so that the bus riders will not have to wait as long to transfer.

Meanwhile, county officials say they have been pleasantly surprised by an increase in reverse commuters who are taking the bus to Herndon/Monroe from Tysons Corner and eastern Fairfax County to go to work at the technology firms that have recently located along the Dulles Corridor.

Fairfax County Supervisor Robert B. Dix Jr. (R-Hunter Mill), who pushed for the funding to build the facility, said about 40,000 workers commute each day to the Reston/Herndon area.

"In actual fact, the reverse commuter makes up over 47 percent of the vehicular traffic on the Dulles Toll road during peak hours," Dix said.

With the growth in the area, a number of other services are being considered for the Herndon facility, including a shuttle bus service to Dulles International Airport for employees who work at various aviation related companies.

"This is a major milestone in our program to expand public transportation choices in the Dulles Corridor," Dix said.