Fairfax County wants more than $1 billion from the federal government to relieve traffic created by the Pentagon when it forced thousands of government employees to relocate to Fort Belvoir and the Mark Center without making necessary transportation improvements.

The Pentagon shifted an additional 20,000 employees to the area as part of its base-closing effort, exacerbating already heavy congestion on local roads. The Fairfax County Board of Supervisors now says at least 18 transportation projects are needed to decrease traffic flow and wants Uncle Sam to foot the bill.

The county wants $600 million for public transit enhancement to Fort Belvoir, at least $245 million to build interchanges and at least $115 million for other improvements to heavily-used roads like Beauregard Street and the Fairfax County Parkway.

The county is also hoping to get some financial relief from the state. Local officials asked Virginia lawmakers to eliminate a program created in fiscal 2009 that requires localities to return funds to the state to help it deal with it's own revenue shortfall. That change would save Fairfax $20 million.

Supervisor Jeff McKay, D-Lee, said the county has sought funding for most of the transportation projects before. But as in years past, McKay expects to get much less than the county requested, particularly since the federal government is dealing with its own budget problems.

"Obviously we know what the political climate is right now," McKay said, "and we're pushing to fight the 'fiscal cliff' and keep our federal contractors. We have no great expectation for funding, but we don't want to let people off the hook."

Lawmakers last year secured $180 million to widen Route 1, but county officials say it wasn't enough to ease traffic problems for the 12,000 employees at the Fort Belvoir.

Additional work is also needed around the Mark Center to accommodate about 6,400 employees who now arrived there everyday. The Mark Center is actually along Interstate 395 in Alexandria, but it hugs the Fairfax County line and creates traffic on local roadways, officials said.

The shifting of military personnel "has clearly had a big impact on us," Supervisor Pat Herrity, R-Springfield, said.

In addition to money, Fairfax also is asking the federal government to keep in place a parking cap that limits the number of workers who drive to the Mark Center. Officials are trying to encourage workers to use public transportation.

"I can't argue that [the addition of thousands of defense workers] hasn't been a huge positive economic benefit for the county," McKay said. "We're continuing to hope for creative solutions to solving our transportation needs."