Fairfax County has approved a major rezoning for a 2.9 million-square-foot office park near Washington Dulles International Airport that may set a precedent for demands placed on other projects in the rapidly growing Rte. 28 corridor.

As a result of the county's action, developers owning different parcels may have to join together to make what the county deems badly needed traffic improvements -- even if some are not seeking major rezonings, developers and county officials said.

After more than 10 months of negotiations and several delays, the Fairfax County Board of Supervisors recently approved construction of the giant office park on more than 87 acres along Coppermine Road south of Herndon.

But Batman Corp., developer of the site, had to convince owners of two large nearby chunks of land already zoned for commercial use to help pay for improvements to the Rte. 28/Frying Pan Road intersection before winning approval for its project.

John Thillmann, the county planning commissioner within whose magisterial district the area lies, said the project "ought to be a model for how the public and private interest can converge. . . . I think this application really sets a high standard for development."

Thillmann said he now has "got a model that I'm going to point to and have other people look at what can be done" when a proposal would affect land other than that involved in a land-use change.

Batman Corp., Pomeroy Investments Inc. and Webb-Sequoia Building Corp. signed a complicated agreement promising to build an interchange at what will be a new intersection of Rte. 28 and Frying Pan Road when developers complete promised road improvements.

Pomeroy owns industrially zoned land south of the Batman tract, while Webb-Sequoia owns 48 acres north of the Batman site near the Rte. 28 and Dulles Toll Road intersection.

Charles Shumate, attorney for Batman, said the agreements to improve Rte. 28 and Frying Pan Road were "in the best interest of all property owners. The road improvements are needed to service all the projects that eventually will be built in the area."

Ray Smith, president of Webb-Sequoia Development, said the joint agreement would be especially good for a hotel project on his company's land that is part of a 1.5 million-square-foot commercial development planned for the site. Construction will begin next spring on the 300-room Hyatt Hotel, which will be close to the Rte. 28/Dulles road interchange, he said.

"We didn't need to do anything, but we formed an agreement to build the roads . . . because we thought it would be good access to our hotel and office development," Smith said.

Neither Webb-Sequoia nor the Pomeroy group was required to make any deals because their land already was zoned for commercial purposes. Batman sought their cooperation, Shumate said.

County planners said the joint road agreement was pivotal to the final approval of the project, for which an application was filed in January.

According to Shumate, the Batman group will realign the section of Horse Pen Road that runs through its land and eliminate that road's access to Rte. 28, a move traffic planners said should help ease traffic problems in the heavily congested area.

Before granting approval, the board of supervisors accepted a long list of promises from the developer. These included: Widening of Coppermine Road along the property's north side. Construction of a four-lane road through the Batman property to connect with Coppermine Road. Dedication of a right-of-way for the eventual realignment of Horse Pen Road. Promises not to allow use of buildings within the development for motor freight terminals, lumber yards, recycling centers or vehicle service establishments.

Robert Newbill, vice president of Batman Corp., said final development plans are not ready.

"We will build a corporate-type office park," Newbill said. "We do The rezoning of the Batman Corp. site "ought to be a model for how the public and private interest can converge. . . . I think this application really sets a high standard for development." -- planning commissioner John Thillmann think this particular piece of ground is one of the better pieces of land in the area of the Dulles Road and Rte. 28." The recently granted rezoning would permit Batman to build seven-story structures. Newbill said his company "might go back to the county" for an increased height on part of the site once development plans are better defined.

Newbill ruled out the possibility that the site would be used as a rail station site if efforts to build a rail line from the West Falls Church Metro Station to Dulles airport succeed. The Metro station is set to open next summer.

Bahman Batman Ghelidj, head of Batman Corp., has been a driving force in the attempt to get a light rail line built to serve the Dulles corridor.

The resolution of the 87-acre Batman proposal is certain to play a role in the final decision on a major land-use proposal pending for 347 acres east of the Batman and Webb-Sequoia sites, Shumate and some landowners agreed.

Almost a year ago, landowners James and Betty Mills, William Moncure, Stephen L. Best, Carlayne and Lee Holloway and J. Horace Jarret asked Fairfax County to change its comprehensive land-use plan for almost 100 acres they own along Centreville and Fox Mill roads from residential to commercial. The landowners envisioned corporate or high-technology development.

Soon after, Thillmann requested that 250 acres owned by Batman Corp. be added to their proposal so that the entire area could be studied in depth. Last April, Thillmann directed that a citizens task force be set up to study the entire tract.

However, members of the study group were named only a few weeks ago. The group is headed by another member of the county planning commission, Al Thomas.

Landowners and residents of nearby communities, including Greg Roy, a residential community surrounded by the open land that owners want to see developed for commercial purposes -- are involved in the study.

Dewberry and Davis, a Fairfax engineering and design firm, is working on a development plan for the entire 347 acres, Shumate said. Moncure said landowners are anxious to see what is proposed by the engineering firm.

Several landowners said they were wary of the study because it is being funded by Batman. However, they said a specific proposal might be what is necessary to get the county to take some action.

Moncure said this week that the county has "doubled my taxes" on the land and has yet to act on the proposal so he can try to get it rezoned or sell it and let someone else handle the rezoning. The study group is expected to come up with a proposal for county review before Christmas.