Developers and landowners with competing interests in Tysons Corner have proposed creating a second Tysons area tax, one that would contribute half of the $507 million needed for road improvements considered crucial to turning the sprawling area into a Metro-accessible urban neighborhood.

Commercial landowners in Tysons already pay a self-imposed tax that is providing up to $400 million in funding for the first phase of the Silver Line Metro extension, currently under construction.

The prospect of a second tax has become a matter of contention among landowners because some are planning new development and require zoning changes while others are content with the development rights they have and oppose the creation of a new tax.

But board members from the Tysons Partnership, a coalition formed by landowners, voted June 11 to recommended that a Tysons area tax be created to pay half of the $507 million, or $253 million.

The other half would come from landowners with active zoning applications, a group that includes Cityline, Capital One and the Georgelas Group.

The group agreed to the funding mechanism under the condition that no additional transportation projects be added to the list, that various financing options are made available to zoning applicants and that the partnership be allowed to review the costs before a tax rate is determined.

Michael Caplin, the Tysons Partnership’s new (and first) executive director, said the vote was not unanimous and he expected that opponents would voice their concerns at a June 21 public meeting of the Fairfax County board.

The $507 million represents only about 40 percent of the total costs of the road improvements, which include adding lanes to Route 7, connections to the Dulles Toll Road and a Beltway overpass. Planning commission staff has recommended that the remaining $701 million come from federal, state, regional and county government sources.

“The Tysons-wide road improvements will benefit all residents and landowners who live, work, play and shop within Tysons, whether they are new office workers or long-time residents,” planning commission staff wrote in making its recommendation. “Therefore, a portion of the cost of the improvements should be borne by all Tysons landowners.”

The county said a total of $2.1 billion in transportation upgrades are needed for Tysons through 2030, for a new network of streets, public transit and pedestrian access.