Fairfax County's leading business group is teaming up with two longtime foes to push for transit improvements and other so-called smart growth initiatives, saying the alliance provides the best chance of finding solutions to the area's worsening traffic problems.

Yesterday's announcement by the Fairfax County Chamber of Commerce, the Piedmont Environmental Council and the Coalition for Smarter Growth marks the latest political coup for slow-growth advocates who, through election upsets and fund-raising, have fast become major players in the regional debate over transportation and development.

Leaders of the three groups--gathered in a law firm's conference room atop a Tysons Corner skyscraper--said they will jointly lobby local and state politicians to speed up funding and construction of a $1.6 billion rail line to serve the rapidly growing Dulles corridor.

The groups will also push to have more land set aside for parks, to provide tax credits for employers that encourage workers to use public transit or work from home, and to encourage revitalization of the Route 1 corridor along with commercial expansion elsewhere.

Both sides--which began talking about two weeks ago at the behest of chamber Chairman James W. Dyke Jr.--stressed that they had not changed their positions on major issues of disagreement such as proposals to widen Interstate 66 or build a new bridge across the Potomac River.

"The agreement is to seek points of consensus," said Christopher G. Miller, president of the Piedmont group. "It's not going to require us to back off on issues we feel strongly about."

By joining together on several fronts, Miller and others said, the groups stand a better chance of persuading state and local officials to push for those projects. In the upcoming General Assembly session, for example, state legislators and Gov. James S. Gilmore III (R) are expected to debate the idea of buying rural land to protect it from development, while Fairfax supervisors are about to craft a new development policy for established neighborhoods.

"Elected officials are getting conflicting signals listening to us shouting at each other," said Dyke. "This sends a clear message to our elected officials that these are issues we should move on."

The alliance is noteworthy considering the long history of conflict between the groups. "There has almost been a prohibition on these groups being in the same room," observed Miller.

The Coalition for Smarter Growth, for example, has consistently criticized the Fairfax chamber and other business groups for relying too heavily on new roads to solve transportation problems. Chamber officials, meanwhile, have often portrayed slow-growth activists as out of step with public opinion.

CAPTION: Interstate 95 traffic backed up for miles after an accident in Fairfax County in June. A coalition is pushing for "smart growth" in the area.