The Fairfax County Board of Supervisors voted to approve a funding deal for the second phase of Dulles Rail Tuesday.

The deal cuts the cost of the second phase from about $3.8 billion to $2.8 billion and requires Fairfax County to fund the construction of a rail station and two parking garages.

Loudoun County, the Metropolitan Washington Airports Authority, the federal government and Virginia Gov. Bob McDonnell already have signed on to the agreement, though McDonnell now must clear $150 million in state funding through the General Assembly.

The second phase of the rail project will extend from Reston to just past Washington Dulles International Airport in Loudoun County. The first phase is already under construction and is promised to open in December 2013, though contractors must make up some delays before that can happen.

Leaders in the project say they are still worried that Dulles Toll Road users, who are paying for most of the rail line, will be paying too much in the future. MWAA is now considering a public-private partnership to help keep toll contributions down.