A traveler heading west through Gainesville, toward the Blue Ridge Mountains might speed past Milton Meckler's four-acre parcel of land facing Route 29 without a second glance. The patch of scrub land with a half-built house next door, and a trailer park and a junkyard nearby, has nothing that invites one to ease off the gas pedal.

Yet Meckler is asking $567,488 for the plot.

Meckler's price -- almost double that offered for commercial land in Gainesville 10 months ago -- is one barometer of the pace at which land values are escalating around the scraggly crossroads where Route 29 joins Interstate 66.

A year ago, Gainesville was a truckers' haunt, offering little more than five gas stations, coffee at Phil's Market and a palm reader where the wary might learn of fate or fortune on the road ahead. Today, land brokers say the crossroads is frequented by business-suited financiers from Washington, New York and Maine.

Real estate brokers say Gainesville has attracted some of the more intense land speculation in Northern Virginia.

Sue Coe, a real estate broker with Mount Vernon Realty, said, "The very best of the property in Fairfax County has been eaten up, and there's no place to go but out. It's sort of like an explosion."

Triggering the upswing in land prices was the news that leaked out this summer that Robert Trent Jones Sr., the internationally acclaimed golf course architect, was buying 845 acres alongside Lake Manassas for a resort with championship golf courses, hotels, homes and a corporate office park. Jones' purchase put Gainesville on the map, brokers say.

Before that, said Anne Wilkins, the broker for the Jones property, she had difficulty convincing bankers that Gainesville had a future. They thought $3,500 an acre was an extraordinary price for Jones to pay for his land when no other parcel had sold for that price in the area before, she said.

Now it may prove to be a bargain. Some large farms around Gainesville without water and sewer services are commanding substantially more than the $3,500-an-acre value placed on the Jones property late last year. Wallace F. Holladay, president of the Washington-based development firm that bears his name, in March paid $6,116 an acre for a 327-acre farm zoned for agricultural use in Haymarket.

And prices today have escalated even further. Michael Giguere, a zoning attorney with the Fairfax firm of Boothe, Prichard and Dudley, said that five years ago he would write contracts for $2,000 an acre for Gainesville land designated in county plans for industrial use.

"Now it is almost impossible to find anything for less than $20,000 an acre," he said.

But Jones' planned investment is only one factor spurring the speculation in Gainesville land. The groundwork was laid when I-66 inside the Capital Beltway was opened in 1982 through to Washington, making the District only a 40-minute drive away. At the same time, development increased around Washington Dulles International Airport and the Route 28 and Route 50 corridors in western Fairfax, pushing land speculators and some warehousing and distribution businesses westward in search of cheaper land.

They began choosing Gainesville when Prince William County brought sewer lines to Haymarket. One of the early pioneers in Gainesville was Eugene I. Siegel, a Bethesda-based land consultant. He has just won approval from the Board of County Supervisors to build a 1-million-square-foot business park on 101 acres at the intersection of Routes 29 and 66, making himself the first speculative developer in Gainesville.

Until Siegel's project was approved last month, no sizable commercial developments had located at Gainesville since the now-failing Atlas Ironworks opened its foundry beside the railroad in 1969.

Siegel's move was followed by Centennial Development Corp.'s announcement two weeks ago that it plans a corporate office park suitable for high-technology businesses on the 514-acre site it is purchasing from Marriott Corp.

Centennial's property, considered the most prestigious office site in Prince William County, is located on the north side of I-66, between Manassas National Battlefield Park and Gainesville.

Although major land deals such as these are crystallizing the future of Gainesville, the area cannot blossom before public water service reaches the crossroads, according to Roger Snyder, the county's planning director.

But the water problem may be resolved within a year. John Bailey, director of engineering with the Prince William County Service Authority, is negotiating with developer Lloyd Cowne, who is building homes south of Gainesville, and with Siegel over how much each property owner should pay toward running a water line from Manassas up Linton Hall Road to Gainesville.

Closely following these negotiations is Zuchelli, Hunter & Associates of Annapolis. The land-consulting firm has a contract on a 331-acre tract in the northern quadrant of I-66 and Route 29, where it plans to build an equestrian community. The county's planning commission is scheduled to hear the application this month.

Housing, however, is not what Prince William officials have in mind for Gainesville. County plans designate the area as a major employment center, and Gainesville Supervisor G. Anthony Guiffre said he has little sympathy for residential development that puts pressure on county services while contributing little to the county's tax base.

Despite the boom-town picture brokers paint of Gainesville, some also are whispering words of caution.

"You've got a hiked-up market right now," said one broker who asked not to be identified. Coe agreed.

Still, few doubt Gainesville's day is coming; the only question is when.