The Prince William Board of County Supervisors last week approved the county's largest commercial and industrial development, but unless the real estate market improves, construction is years away.

If the Broadview Center project is completed, it would bring as much as 15 million square feet of commercial, retail and industrial space to the northwestern side of the Manassas Airport. The project is similar to Westfields, the Henry Long Co. development that is one of Fairfax County's largest office and industrial parks, said developer Russell T. Aaronson Jr.

Aaronson said he envisions completing the project, which would be bisected by the planned Route 234 bypass around Manassas, in 15 to 20 years. But he has not looked for financing for the development, and acknowleged that finding a lender could be difficult.

"My hope is that the {slow} market we're in will improve," Aaronson said. "If that doesn't happen, I will have my {zoning} approvals and just sit on those plans and wait for the {tenants} to come back."

The Broadview Center plans call for 681 acres of low, light-industrial buildings, 187 acres of general business usage and 103 acres of office highrises, including buildings of up to 10 stories at major intersections and along the bypass.

To mitigate the effects of the enormous development, Aaronson offered, and the board accepted, a package of road and other improvements valued at $65 million. Aaronson agreed to widen Route 28 to four lanes, pay extra taxes to help fund construction of the bypass, donate right-of-way for the road institute measures to reduce traffic, such as shuttle buses and incentives for car pools.

Despite its size, the Broadview project passed with little dissent or even much comment. Only a few people spoke about the project at a Planning Commission meeting or before the supervisors.

The easy passage stemmed from the project's ability to bring up to 43,000 jobs to this bedroom community, where more than half of all workers commute to jobs in jurisdictions to the north.

Unlike most earlier large rezoning requests, Broadview Center has no residential component. New housing developments generally are more controversial because they require more money and services -- such as schools and human services -- than they generate in new tax dollars.

Commercial developments do just the reverse, and Aaronson estimated that Broadview would generate $21 million in new tax revenue.

The Aaronson project is in the middle of the area county officials have long targeted as their commercial and industrial growth corridor, and local officials see the project as evidence their economic development efforts are working.

"We're going to bounce back quicker than other people and that development {Broadview} will help. God knows we need it," said Robert L. Cole (D-Gainesville), chairman of the Board of Supervisors.

Representatives of the Northwest Prince William Citizens Association, which has a reputation for looking skeptically at development, spoke in favor of the project. "It was clearly consistent with the comprehensive plan and they seemed to have proffered a significant amount of road improvements," said the association's president, Richard Hefter.

The one note of dissent came from environmentalists, who expressed concern that the project would disrupt the habitats of loggerheaded shrikes, migrating birds on the federal endangered species list, and barn owls, both of which nest in the area.

The developer promised to protect the owls by preserving the silos where they nest or relocating them, and to abide by state laws that require developers to set aside land for endangered species.