A Prince William circuit court judge ruled this week that the Board of County Supervisors acted within its legal power when it opted to use road bond money to build a new mid-county road rather than widen existing Davis Ford Road.

Chief Judge Frank A. Hoss Jr. ruled Monday against the two "objections" filed by county residents who oppose the county's plan to use $20.2 million from a 1988 bond referendum for an eight-mile, four-lane road, saying they were both procedurally and substantively invalid.

County residents who oppose the new road had said that because the referendum said the money was for "improvements to the Davis Ford Road . . . corridor," the county could not use the $20.2 million for a new road that will parallel crowded Davis Ford between Hoadly Road and Liberia Avenue.

But Hoss ruled the plaintiffs had not used the correct form for challenging the road construction. "I have never seen anything like what they filed. Why they chose that form I have no idea," Hoss said after handing down his decision.

Hoss ruled that the ballot question "sufficiently described" the way the money would be used, and that the board had correctly validated the election results.

The ruling came as a relief for county officials, who have been waiting until the legal problems were cleared up before hiring an engineer to design the new road. The Board of County Supervisors probably will vote to award a design contract next week, said Thomas J. Blaser, chief of transportation management.

But the issue hasn't been completely put to rest.

The 1988 referendum included money only to buy land and design the road.

The supervisors plan to ask the voters this fall to approve a second bond sale to fund the additional $43 million needed to build the road.