In a coup for Virginia, federal highway officials have cleared the way for the state to receive $300 million in interstate highway construction money to extend rush-hour car pool lanes on the Shirley Highway 19 miles from Springfield to Quantico.

Only $13 million usually is distributed to Virginia each year for new interstate highway construction, so a one-time allocation of $300 million could free other federal money for construction on the Capital Beltway and Interstate 66.

Virginia Transportation Secretary John G. Milliken, in announcing the award late yesterday, said that part of the $300 million would be used for interstate projects in the Richmond and Norfolk areas, but that the bulk of the money -- $237 million -- would go toward the completion of the Shirley Highway restricted lanes.

Gov. L. Douglas Wilder, whose administration has been working behind the scenes to obtain the money, called the Bush administration's decision "a critical step forward for Virginia."

Fairfax County Board Chairman Audrey Moore said, "What it means is Interstate 95 {the Shirley Highway} will get HOV {high occupancy vehicle} lanes right away."

The Shirley Highway project, one of the state's largest, began last year and contributes to the congestion along one of the region's busiest travel corridors.

When completed in 1994, the highway will have permanent, reversible car pool lanes from the 14th Street Bridge in the District to just south of the Prince William County line at the Occoquan River.

Before yesterday, the $237 million cost of the project was to come over five years from a category of federal highway funding called "4R" -- restoration, resurfacing, reconstruction and rehabilitation. Virginia gets about $70 million a year in the category to spread throughout the state on interstate projects.

Virginia officials, working with the state's congressional delegation, persuaded federal officials to finance the four Virginia projects from a different category -- new interstate construction -- that makes about $3 billion available to the states.

Virginia gets an added bonus. About $50 million that the state would have had to spend from the 4R program on the four projects now will be freed for other critical interstate work around the state, such as the Beltway and I-66.