A growing number of Fairfax County residents and anti-sprawl activists are organizing to fight Virginia's plans to enlarge 10 major interchanges along the Capital Beltway and add up to four lanes to the jammed highway.

State transportation officials began a series of meetings last night -- to be continued tonight and tomorrow -- designed to give residents a view of possibilities for expanding the eight-lane roadway.

As residents of the Annandale area pored over maps and diagrams last night inside Poe Elementary School, about a dozen members of a slow-growth group demonstrated outside with placards and handouts. The group said its members would protest at each of this week's Beltway meetings, hoping to send a strong message.

"We are coming together as one to fight the Beltway. We are telling officials to stop the Beltway and look at other things like rail, and listen to the citizens," said Nikki McClain, who lives in the shadow of the Interstate 66 interchange with the Beltway and has helped organize a group of local civic associations opposed to the expansion. "They can't pave their way out of this kind of gridlock."

Resident opposition to Beltway expansion is strongest in neighborhoods near the highway, especially in those close to interchanges that would have to be expanded to handle more traffic heading to and from the busy road.

Some residents fear they could lose their homes to additional asphalt or find their real estate impossible to sell because of uncertainties surrounding the future projects. Many also say the quality of life along the Beltway would seriously suffer if the road is widened.

"I'm concerned about the noise and the pollution," said Claremont Pederson, 73, a homeowner on a road parallel to the Beltway near Braddock Road. "It's noisy now. My God, what's it going to be like when they get it expanded?"

Advocates of Beltway widening say something has to be done or the transportation crisis in Northern Virginia will choke off the region's economic gains.

"If we do nothing, commuting times will increase by 100 percent," said Ken Wilkinson, Beltway project manager for the Virginia Department of Transportation. "More accidents will occur, and backups will stretch for several miles. Average speed will decrease to less than 25 mph, and local and regional air quality will decline."

Plans under consideration by Virginia officials include a pair of 10-lane designs and two 12-lane concepts that would include car-pool lanes or separated local and through-traffic lanes, or some combination of both.

Opponents say the addition of more lanes to the Beltway will only invite more traffic. They suggest that Virginia planners seriously consider adding mass transit to the Beltway -- an alternative under consideration by Maryland planners for its 44-mile stretch of Beltway but rejected by Virginia.

VDOT planners determined that rail on the Beltway would decrease traffic on the roadway by only about 5 percent. But recently, a Fairfax citizen task force recommended revisiting the idea of mass transit on the Beltway and called for a full-scale environmental study of the project.

Maryland is considering a variety of other ways to add capacity to the Beltway, such as adding special Beltway bus service and even including car-pool lanes that single drivers can enter by paying a toll.

Transportation planners in both states agree that something must be done to increase the numbers of commuters able to use the region's "main street." The Beltway is increasingly clogged with suburban commuters trying to get to jobs in burgeoning job centers such as Tysons Corner and Rockville. About 220,000 vehicles use it every day, and planners estimate that the load will increase by 41 percent by 2020.

Maryland residents will have their chance at more public meetings in the fall, when state officials plan to discuss the pros and cons of transit versus adding lanes.