Dozens of Virginia highway construction projects scheduled to begin during the next three months, including several major Northern Virginia projects, have been postponed indefinitely because of an expected shortfall of $15 million in this year's state highway revenues.

This year's decreased revenues, coupled with further declines expected next year, according to state highway officials, probably will mean a budget for the coming fiscal year that is $50 million less than the current $850 million budget. The new budget proposal, totaling about $800 million, is expected to be approved today at a meeting of the Virginia Highway and Transportation Commission.

In Northern Virginia, according to state officials, this year's shortfall could delay at least three projects, all to widen or replace two-lane roads with four lanes.Those projects include Rte. 123 from the Fairfax City courthouse to Occoquan, Rte. 50 in Loudoun County, and Rte. 7 west of Leesburg to Purcellville. Construction bids were to have been let on all of three projects within the next two months.

At a series of public hearings last week, county and city officials across the state pleaded for billions of dollars for what they termed "crucial" and "absolutely essential" road projects -- far more than the $700 million expected to be available for actual road projects. While the official highways budget is expected to total $800 million, more than $92 million goes to other state agencies, such as the Division of Motor Vehicles.

"(Local governments) are asking for more than 10 times the money that's available," said Al Coates, spokesman for the state Department of Highways and Transportation. "In Suffolk alone, for example . . . the Norfolk, Virginia Beach, Portsmouth area . . . they're asking for more than $1 billion for what they consider essential road projects. There's going to be a lot of vying for limited state funds."

At a hearing in Fairfax City last week, Northern Virginia officials added their requests to an already burgeoning pile of pleas.

Dayton Cook, Alexandria's director of transportation and environmental services, said, "We must appeal for more than our share . . . we need it (state money) so badly." He pleaded for funds to improve Duke, King and Van Dorn streets, to build a new Monroe Avenue (Rte. 1) bridge over the Potomac Rairoad Yard, to build two other bridges and to complete the city's new computerized traffic light system.

Loudoun County Supervisor Thomas Dodson said, despite the state highway budget crisis, the county must have improvements "on its woefully inadequate primary roads." He listed as priorities the widening of Rte. 7 to four lanes, construction of the Springfield Bypass, a new highway paralleling Rte, 28, and widening Rte. 50 to four lanes.

Fairfax County is submitting a written request for continued state support of mass transit and for numerous road widening or improvement projects, including Rte. 123, Georgetown Pike and routes 1, 50 and 7.

Arlington County, one of only two Virginia counties to maintain its own roads, included among its requests funds for a new road paralleling Wilson Boulevard near the county courthouse and the widening of Rte. 1 through Crystal City.

The total cost has not yet been tallied for projects requested by the 13 Northern Virginia countries and cities, which are administered by the highway department's Culpeper district. However, Culpeper already gets more money than any of the other seven highway districts in the state. Since funds are allocated based on such factors as population, number of miles of roads and number of registered vehicles, Culpeper, with the growing Washington suburbs, has been getting increasing percentages -- but of a dwindling state highway budget.

This is the second year in a row that Virginia has cut back road projects because of declining state revenues. Last year, revenues were $44 million less than expected.

Although funds for interstate highways and general highway maintenance are expected to increase slightly, funds for construction and reconstruction of state roads and bridges and funds for local street projects are expected to drop 37 percent to 51 percent.

State highway officials attribute the decline in revenues, derived primarily from the 11-cents-a-gallon gasoline tax and the 2 percent motor vehicle sales tax, to three factors: Motorists are driving less, buying fewer cars and the cars they have been buying get better gas mileage.

Under the budget proposal expected to be approved today, major allocation would include:

Primary road improvements: $46.9 million, down from the current funding of $96.2 million.

Secondary road improvements: $41.7 million, down from current funding of $68 million.

Street construction funds for cities of at least 3,500 (Alexandria, for example), which construct and maintain their own streets: $39.5 million, down from current funding of $62.3 million.

Maintenance of all highways, streets and bridges: $222 million, up from current funding of $197 million.

Interstste highways: $210 million, up from $205 million.

The state highway commissionis expected to hold hearings on the proposed allocations in mid-June.