The Prince William Board of County Supervisors decided two roads are better than one last night, voting unanimously to build an entirely new road through the county's mid-section rather than widen a crowded existing road.

The $57.3 million package the board approved last night includes a new eight-mile, four-lane road between Liberia and Hoadly roads and $7 million in safety improvements for existing Davis Ford Road. The county also will buy enough land to ensure that the new road could be expanded to six lanes.

"It's the logical decision to make in terms of safety and transportation needs," said supervisor Kathleen K. Seefeldt (D-Occoquan).

One of only two cross-county routes, two-lane Davis Ford Road is a major commuter route and one of Prince William's most dangerous roads. The realignment plans have been mired in controversy since February.

Last night's unanimous vote came after 2 1/2 hours of deeply divided public testimony, in which citizens warned that the wrong decision would lead to uncontrolled growth, years of construction delays and multi-car accidents.

Supporters of the new road bolstered their claim that they represent the majority by presenting more than 1,200 signatures on a petition favoring the project.

The controversy that blossomed this spring had its roots in the supervisors' decision in 1988 to seek $66 million in road bond funds for projects including improvements in the Davis Ford corridor. When residents along the existing road complained, the supervisors agreed to consider alternative alignments, and the bond issue was easily approved at referendum.

Last winter, a consultant working with a citizens committee found that widening the existing road would cost $20 million more and displace more houses than building a new road, because the a wider version of the existing road -- called Alignment A -- would need service drives for local traffic.

Mid-county homeowners alleged voter fraud, saying the 1988 bond referendum failed to make clear that the money might be used for a new road.

"Citizens knew we were going to widen Davis Ford. We should not spring a surprise on them," said mid-county resident William J. Doyle.

But Deborah Hunt, a supporter of the road, called Alignment B, said, "I want to make the decision on information we have now rather than on information we had two years ago."

The supervisors also rejected citizens' calls for widening Davis Ford without building service roads. Public works officials estimated that widening to four-lanes would cost $39.5 million. The staff warned against a simple widening because scores of existing driveways would open onto the resulting four-lane road, posing major safety hazards.

Last night's vote does not end the debate. The supervisors must go back to the voters this fall with a new $37 million bond referendum to pay for construction of the road.

The 1988 bond issue only included enough money for design and right-of-way purchase because public works officials could not estimate how much the road would cost until the supervisors picked an alignment.