Prince William County's efforts to upgrade its antiquated, rural road system so it can handle traffic generated by a decade of growth may have run smack into two very large roadblocks in the forms of a financially strapped state government and Fairfax County's John F. Herrity.

And if the sentiments of Fairfax County Board of Supervisors Chairman Herrity are any indication of Prince William's chances of getting their roads built, then things look pretty bleak.

"They can take that road and go fly a kite," said Herrity last week of a Prince William plan that would see Ridgefield Road in the eastern half of the county bridge the Occoquan River, then hook up with the Fairfax County road system. "They can build their half of the road and swim over the Occoquan for all I care."

The traffic-choked roads of Prince William are "our number one problem," said county planner John Snyder. "Our projections show it's going to be hell. I look at problems and try to see solutions. I look at our road situation and all I can see is gloom."

From businessmen to commuters to county officials, the assessment is the same: The major problem facing continued development in the county is the state of the county's roads.

"It will take decades to completely alleviate our traffic problems," said Kathleen Seefeldt, chairman of the Prince William County Board of Supervisors. "We consider this our most pressing problem in the county at this time."

So concerned are county officials that last week they trekked to Richmond to enlist the support of Gov. Charles S. Robb for one $70 million bypass program. Although they were successful in winning him to their cause, coming up with the money may well be another thing altogether in a state where Robb himself says belt-tightening is going to be the rallying cry for the foreseeable future.

"Obviously, we didn't walk away with the project in hand and the money in our pocket," Seefeldt said two days later at a local chamber of commerce seminar. "However, the governor responded very positively."

At issue are two projects:

Widening Rte. 234, the county's major east-west route, into a four-lane highway, and in the process constructing a 22-mile bypass from the highway's start in the Bull Run Mountains to just past Manassas;

Extending Ridgefield Road across the Occoquan into neighboring Fairfax County, where it would cross Rte. 123 and eventually hook up with the proposed Springfield bypass.

The Rte. 234 bypass has generally received support from both county residents and highway officials. However, its estimated $70 million price tag has put a damper on the enthusiasm of state highway officials. David Ogle, resident engineer for the Virginia Department of Highways and Transportation, noted that there is far less state money available for highway construction than there has been in past years.

State funding available for road projects in all of Northern Virginia is estimated to be $13 million next year, an amount that will drop to $10 million the year after that, and finally to $5 million for each of the two succeeding years, he said.

Despite the potential funding problems, the county is forging ahead with plans for the new roads. There is no alternative, according to county planner John Snyder.

The past decade has been one of unprecedented growth in the county. According to census figures, once-rural Prince William almost doubled its population to 140,000 between 1970 and 1980. Most of the newcomers moved to subdivisions in the eastern end of the county. Most commute to jobs in and around the District of Columbia 30 miles away.

"In this situation, when you've got paved-over cowpaths, you've got trouble," said Snyder.

At all hours, the traffic on such cross-county routes as Davis Ford Road (Rte. 28) and Rte. 234 is heavy, said Seefeldt. During rush hours, the backups to the entrance ramps for I-66 and I-95 can stretch for miles.

To compound the problem, Prince William is attempting to lure businesses to settle in recently zoned industrial parks as a way to broaden the county tax base. The county can offer financing, a labor force and acres of open land to businesses seeking to relocate.

But they can't hide the fact that the county's two-lane roads are ill-equipped to handle the traffic new businesses will create.

County leaders have not ignored its road problems over the years, however, said Seefeldt. Prince William has been lobbying Fairfax for the Ridgefield Road hookup for several years and she said supervisors will continue to press for the road despite Herrity's outright rejection of it.

Prince William has only five major roads leading across the river towards the District, including I-66, I-95 and Rte. 1. An extended Ridgefield Road would alleviate some of the traffic bottleneck on these three roads, said Seefeldt, as well as providing easy access to Tysons Corner in Fairfax.

However, Herrity said Fairfax County has a long ribbon of park land along its side of the Occoquan and does not want a major roadway cutting through it. He also said Fairfax residents do not want a road full of Prince William commuters going through their neighborhoods.

"I'm not going to stand by and watch a highway go through our park land," said Herrity.

Snyder said even state officials believe the road should be built, however. "The State Council of Governments and the Highway Department agree with us that the road is sorely needed," he said. "Of course, we're not going to build an expensive four-lane overlook of the Occoquan, but we do hope Fairfax will realize that this road would be to their benefit as well and meet us halfway across the river."

Similarily, the county has already set the Rte. 234 project in motion.

The state funded a survey last year to determine the path of the Rte. 234 bypass. The county's next step is to go before the state Highway Department next month and request inclusion in a funding plan that determines road priorities for the next six years.

Federal funds from a recently approved gasoline tax may add to the pot available to the county, said Ogle. "But it is a foregone conclusion that most of the Rte. 234 project is well off in the future."

Ogle said the project will probably be funded piece by piece, starting with widening the road near I-95 and constructing the bypass at a later date.

It is estimated that by the 1990s, 58 percent of the county's population will live within five minutes of Rte. 234, said Seefeldt.

"It is important for the quality of life in Prince William to ease our transportation problems," she said. "It is the major drawback of a community full of assets."