Slow-growth activists, including a woman dressed as a sheep, gathered yesterday in a still-rural part of Loudoun County to warn that a flurry of recent development proposals could add hundreds of thousands of car trips to the region's already clogged roads.

With the rumble of 18-wheelers drowning out some of the speakers gathered along Route 50 at Mount Zion Church, representatives of Piedmont Environmental Council and other groups teamed with a handful of residents to decry a push for more construction in the nation's fastest-growing county.

"We're standing in an area of Loudoun County that's threatened by massive suburban development," said one of the activists, Andrea McGimsey.

In an effort to loosen building restrictions imposed last year, home builders and developers submitted 20 requests in recent months to allow the construction of millions of square feet of commercial space and tens of thousands of additional homes, many of them between the church and Dulles International Airport.

"You can almost parallel it to obesity," said Missy Janes, who was born in Loudoun a half-century ago, when the population was about 23,000. It is now 235,000.

"There's no discipline. It's almost like all the land is calories, and we're gobbling up all the land without thinking what's good for us," said Janes, a member of Piedmont Environmental Council's board.

Yesterday's assembly was part of a campaign by slow-growth proponents as planners gird for meetings at the end of the month to consider the development proposals. Opponents have been parsing the proposals and going door-to-door to tell residents that their quality of life is in danger.

Many Republicans on Loudoun's Board of Supervisors -- which has been controlled by Republicans since January -- have criticized the growth curbs put in place by their predecessors and have bristled at the increasingly vocal critique of their approach.

After speakers assailed supervisors at their regular Tuesday meeting, accusing them of preparing to ram through changes that would benefit development industry campaign contributors, Supervisor Stephen J. Snow (R-Dulles) offered a suggestion.

"If you don't like what we are going to do, then there's other places -- Canada and other places -- you might enjoy," Snow said, adding that slow-growth policies are a way to wreak "death and destruction on a county."

Snow said he is focused on a wide swath of land east of the James Monroe Highway -- U.S. 15 -- which runs between the Prince William County line and Maryland.

"We're not going to pave over or do anything to western Loudoun County," said Snow, referring to the largely rural area that makes up the bulk of the county. "But from east of Route 15, that's land if well used and well organized, we can use for intelligent, managed growth, and that's what we're going to do," he said.

Approving the 20 development proposals would add between 31,000 and 42,000 homes in Loudoun, and 400,000 daily car trips, according to Ed Gorski of the Piedmont Environmental Council. Millions in promised road improvements were not factored into the analysis, he said.

Supervisor Mick Staton Jr. (R-Sugarland Run) called Gorski's figures "scare tactics," because supervisors are far from a decision.