A plan drafted for Loudoun County seeks to limit development in rural areas because of "dangerous" dirt roads, which some say is an unprecedented anti-growth approach in the Washington area.

Those developing rural land, still the majority of Loudoun's acreage, would have to pay for virtually all road improvements needed on and near their residential projects. The proposal says that the state and county governments cannot keep up with highway needs in Loudoun, which grew rapidly in the 1980s and is targeted for significant development in the 1990s and beyond.

The plan proposes shifting the burden of paying for development away from current taxpayers and toward developers during the next 50 years, largely through the untested legal principle that the county should not have to pay to make narrow country lanes safe for residents of new subdivisions.

Some property owners say the Loudoun proposal would reduce the value of their land and would not withstand a legal challenge in a state that traditionally protects landholders' rights.

"I don't know of another jurisdiction in the country" that puts as much burden on the developer as Loudoun proposes, said Sami E. Totah, whose 675-acre Westport project in southern Loudoun could be delayed up to two decades under the plan unless he pays for the roads and other amenities.

"I don't see any justification for it in state law," said David H. Miller, whose proposed 2,100-acre Greenfields development also would be affected.

Developers said the plan would block most potential growth in rural areas. The increased costs to any developer who proceeded would be passed on to home buyers in the form of higher prices, they said.

Virginia laws give local governments the power to implement reasonable planning and zoning tools, yet they protect landowners against having property rights taken without compensation.

Northern Virginia jurisdictions have limited authority to extract pledges that developers pay for a significant part of the public costs associated with their projects. In recent months, Loudoun officials and developers say development firms generally have pledged 20 to 40 percent of the cost of public facilities. Unlike Maryland counties, Virginia localities do not have the authority to halt development in areas where public facilities are judged to be inadequate.

Planning officials say the proposed plan would ensure that Loudoun can absorb its fair share of the region's growth once the area economy and real estate market rebound. The draft, which has been in the works for nearly a year, is being reviewed by the county Planning Commission, and final action by the Board of Supervisors is not likely before early next year.

Members of both panels predict the proposal will be revised. The thrust of the plan has been endorsed by the Piedmont Environmental Council and the National Park Service, which monitors the Waterford village's National Historic Landmark District.

The proposal seeks to concentrate most new development in areas just west of Sterling and Dulles International Airport, where roads and sewers are in place. It also attempts to channel western Loudoun development around existing towns.

"In some ways this is a much more liberal, open and flexible approach than we've taken in the past," said county Planning Director Milton Herd. The plan may make development and housing more expensive, but the policy is not a growth ban, he said.

The plan's introduction says that "no development should cause unduly dangerous roads." Herd said the county is on firm ground legally, adding that "any innovation is always subject to challenge."

Loudoun County Board member Betsey Brown (D-Catoctin), who has called western Loudoun roads "killing fields" because highway deaths have surged in recent years, defends the restriction. "Anybody who has driven on a 12-foot-wide gravel road knows that a large subdivision isn't going to fit on that road," she said.

Jack Hodge, the state's chief highway engineer, said any unpaved road that carries more than 100 vehicles a day is considered unsafe. Nearly half Loudoun's 745 miles of local roads are unpaved, and many are heavily traveled.

Development on mountainsides, near streams and in other environmentally sensitive areas would be subject to detailed regulations under the proposal. The number and locations of parcels zoned for residential use would be limited, and new villages surrounded by open space would be encouraged.