Fairfax County is being asked to consider soliciting public-private partnerships to pay for parking garages and even station construction to help reduce the costs of the Dulles Metrorail extension.

Fairfax County Board of Supervisors Chairwoman Sharon Bulova (D-At large) briefed her fellow board members Tuesday on the progress of negotiations between the rail project's funding partners.

U.S. Secretary of Transportation Ray LaHood has been leading meetings between representatives of Fairfax and Loudoun counties, Virginia and the Metropolitan Washington Airports Authority to reach consensus on cost reductions to the $3.5 billion second phase of the rail project.

LaHood stepped in after public feuding between the project funding partners appeared to be threatening the viability of the rail extension. The airports authority board of directors drew the ire of local elected officials when it decided to retain an underground station at Washington Dulles International Airport, a decision that costs $350 million more and will take longer to construct.

The original cost estimate for the project’s second phase, which would extend Metrorail service to Reston, Herndon, Dulles Airport and Loudoun County, was $2.5 billion. The $2.6 billion first phase, including four stations in Tysons Corner and one in Reston, is now under construction.

Bulova said LaHood asked her to get feedback from the board regarding the possible use of public-private partnerships. A public-private partnership is an agreement in which the government shares the cost of building infrastructure with a private entity. The private partner generally receives some benefit from this, such as development rights or the ability to collect tolls on a road.

The county is using such an agreement to build the parking garage at Wiehle Avenue in Reston, the final station in the first segment of the new "Silver Line." Developer Comstock is building a new development alongside the Metro parking garage.

Some supervisors said they have concerns about allowing for the additional density at the rail stations, which would likely be needed to make a partnership attractive to the private developers.

"It isn’t free,” said Supervisor Michael Frey (R-Sully), noting that new development will require additional county services. "There is huge cost to that, and we’re the ones that have to bear that."

The group was slated to meet again Thursday, after The Times’ deadline, Bulova said. She said she does not anticipate any final decisions coming out of that meeting.

kschumitz@fairfaxtimes.com