Transportation Secretary Elizabeth Hanford Dole agreed to a plan yesterday to open the Dulles Access Road to commuter buses during the morning rush hour. The road has been closed to commuter traffic since the opening of the Dulles Toll Road in 1984.

Under the plan, proposed in November by Rep. Frank R. Wolf (R-Va.), buses will avoid the heavily congested Dulles Toll Road, where traffic jams have become part of the daily routine, and instead rely on the much less crowded access road. DOT approval was required because the access road is controlled by the Federal Aviation Administration.

"This will have a major positive impact on both those roads and on the people who use them," Wolf said yesterday. "It will save time and it will encourage the use of mass transit. I see no down side to this at all."

Officials from the state highway department said that the system would begin operation as soon as the FAA and Fairfax County authorities agree on the details of constructing ramps for the commuter buses near Reston. It has not yet been determined who will pay for the construction or how much it will cost.

Wolf said yesterday he hoped the system would be in place within a month.

He added that he was not certain during what hours the system would be in effect. Initially, only morning travel will be affected, but state highway officials said they would include the evening if it became necessary.

In the past, most of the 16-mile access road has been restricted to airport traffic. The toll road was opened in 1984 as a way to accommodate the growing number of commuters living between the Capital Beltway and Dulles International Airport. Partly because the growth of the region has exceeded even the most optimistic predictions, the volume of traffic on the toll road has become a major problem.

In its first full year, more than 60,000 people traveled on the toll road each day, according to the Virginia Department of Highways and Transportation. The agency had expected slightly more than half that figure.

Wolf said that 37 commuter buses leave Reston each morning and that their travel time between Reston and the District could be reduced by at least 15 minutes under the new system.

"I think this could help alleviate one of the major problems we have in that area each morning," said Lynda J. South, a spokeswoman for the State Department of Highways and Transportation. "We have said it will make a big difference and I am glad the FAA decided it was in the best interest of commuters."

Riders from Loudoun County and Herndon also would be affected by the new system.

Metrobus riders have frequently voiced their frustration at seeing the access road stand virtually empty each morning as congestion on the toll road increased.

In a letter to Rep. Wolf last month, Washington Metropolitan Area Transit Authority General Manager Carmen E. Turner wrote that the system was consistently losing riders along the Dulles Toll Road because of chronic delays.

Complaints have been rising rapidly about Metrobus traffic delays on the Reston and Herndon express routes, according to WMATA.

With Metro's Orange line to Vienna scheduled to open this summer, Metro officials say that a speedy bus trip along the access road will encourage commuters to switch to public transportation.