It is 6:15 a.m. as Bob Singleton wheels his big, baby blue-and-white van out of the parking lot at the mall at Manassas and onto the darkness of Rte. 234 for the long commute to Washington.

Thirty-two minutes later--about 15 to 20 minutes less than it took just two months ago--the van heads over the Key Bridge and into Washington.

"There was a time when people thought you were crazy to live way out in Prince William," said passenger Tod Fisher, a program analyst for the Veteran's Administration, who bought his farm near the Bull Run Mountains 20 years ago. "Now it's considered a fairly easy commute. No one thinks there's anything unusual about it."

I-66, which created an uninterrupted highway from the District to the heart of western Prince William County when its last segment opened Dec. 22, has brought the county closer--figuratively, if not literally--to the District.

As a result, in a county where more than 55,000 people commute to work, according to the county planning office, real estate agents expect an increase in home sales, county planners expect an increase in development and residents expect their growing community to become less rural and more like its more suburban neighbors of Fairfax and Arlington counties.

"My impression is there are a lot of people looking for a little more room who are going to move out here," said Singleton, a technical editor for the Federal Communications Commission and a five-year resident of Prince William. "If it gets too crowded, we'll have to move farther out."

Like many of his western Prince William neighbors, Singleton said he moved out to the county years ago despite a lengthy commute: he wanted room for his three children in a house he could afford.

Until the final section of I-66 opened last month, Singleton's van pool took the Beltway to the George Washington Parkway to the Key Bridge, making the total commute closer to an hour rather than a half-hour.

"I knew I-66 was going to open before I moved in here, but it wasn't a factor in our decision to settle in Manassas," Singleton said. "I think a lot more people who consider commuting time are now going to see western Prince William and Loudoun County as an alternative to some of the higher-priced neighborhoods closer in to the District."

County planner Roger Snyder agrees. "Nothing has started to pop," he said. "But we expect to see a lot of applications for zoning and building permits in that area soon. A lot of property in the west near the interstate has been changing hands as the developers move in."

Snyder said the county recently built sewer lines in a large section of the western part of the county, partly because planners anticipated an influx of resident commuters with the opening of I-66. The more densely settled eastern half of the county has access to the District via I-95.

The opening of I-66 has created other needs in Prince William, which has 145,000 residents and is one of the fastest growing areas in the country, according to recent census figures. Planning officials repeatedly have said the county needs more and better primary roads leading to interstate highways.

Last week, Snyder reiterated the need to expand Ridgefield Road to Fairfax County--an idea that prompted Fairfax supervisors Chairman John Herrity to say Prince William officials "could take their road and go fly a kite."

"I would like to tell Mr. Herrity that we use reason, not rhetoric," Snyder said. "With the opening of the interstate, there will be more and more commuters at his back door. Alternate routes will benefit all counties. Otherwise, Prince William and Fauquier County commuters will compete with the highways used by Fairfax commuters."

Real estate agents, such as Holmes Smith, with Mount Vernon Realty, say they expect an increased interest in homes in the western end of the county. He said a four-bedroom colonial sells for $10,000 to $15,000 less in Prince William than in neighborhoods closer to the District.

"That's an incentive right there," Smith said. "A half-hour to 45-minute commute into Washington is another incentive. It's going to help. It will be another selling point."

All the same, there is some disappointment over restrictions imposed on use of I-66 during rush hours, when it is restricted to vehicles with four or more passengers.

"We've been telling people for years that when 66 opened they would be in Washington in 25 minutes and property values would rise," said Sylvia Tindall, a Realtor for the Holley, Hargett & Spain real estate service. "Then, surprise, no one can use it."

For CIA budget assistant Nancy Wessel, however, commuting was not a factor when she and her husband decided to move back to her home town of Manassas in 1975. They wanted a large house and her children wanted a barn for Chris, their Thoroughbred mare.

"When I was a child, people would have thought it madness to commute into the city," said Wessel, who does so every day in a car pool. "Now Manassas is really a suburb for commuters, and the drive along I-66 is quite fast, probably faster than taking a bus from homes near Washington."

"This is lovely country," she said, a bit wistfully. "I suppose more people are going to discover that now. It is sort of a shame for those of us who lived here when Prince William was considered the ends of the earth."