A Silver Line train runs in Reston, Va., on its opening day in 2014. Zoning changes approved Tuesday by the Fairfax County Board of Supervisors will allow higher density development near new Metro stations. (Yue Wu/The Washington Post)

The Fairfax County Board of Supervisors has approved changes to zoning requirements that allow for higher buildings near Metro stations and in aging commercial areas targeted for redevelopment.

The changes, which the board unanimously approved Tuesday, allow for denser development in 22 areas of the county, including Reston, Seven Corners and the Richmond Highway corridor.

The new zoning guidelines increase the maximum allowable floor-area ratios, or FAR — a measurement used to determine density in buildings that accounts for ground-level retail stores and parking garages.

Under the new rules, the maximum FAR for most of those neighborhoods rises from 2.0 or 3.0 to 5.0. A 5.0 FAR is equivalent to a 10-story building with 50,000 square feet on each level. The board carved out an exception for downtown McLean, which will have a maximum FAR of 3.0, officials said.

During a public hearing Tuesday, Fred Selden, director of the county’s Planning and Zoning Department, said the new density limits comply with planning guidelines already in place for the targeted neighborhoods.

The overall idea is to allow for more buildings in those areas that have ground-floor retail stores and underground parking, Selden said.

“That’s the direction we’re asking developers to go in for those areas,” he said. “We’re talking about small parcels of land in some of these neighborhoods.”

Residents in Seven Corners, Reston and some other affected areas argued that the changes will open the door to high-rise apartment buildings in neighborhoods that are already overwhelmed by traffic congestion.

“These are not insignificant changes,” said Rob Whitfield, an activist in Reston, where residents are seeing more traffic resulting from new townhouse complexes recently built near the area’s two Silver Line Metro stations.

“The result of the high-rise buildings that will come under what is now allowed is certainly not conducive to family upbringing.”