The Dulles Corridor Metrorail Project (Silver Line) is a new 23-mile extension of the current Metrorail system, branching from the Orange Line’s East Falls Church Station in Arlington, Virginia to the Washington Dulles International Airport and west to eastern Loudoun County.

The project is adding 11 stations and includes the construction of a new rail yard on Dulles Airport property and procurement of 128 railcars. Upon completion of the project, operation will be transferred to the Washington Metropolitan Area Transit Authority (WMATA), the operator of the existing Metrorail system.
The project is being constructed in two phases. Phase 1, which opened in July 2014, runs 12 miles from East Falls Church to Wiehle Avenue in Reston. This phase included five stations to the Silver Line, including four in Tysons Corner. Phase 2 continues 11 miles from Wiehle Avenue to eastern Loudoun County. This phase is adding six stations, including stops in Reston, Herndon, Dulles Airport, and in Ashburn.

The extension will serve the largest employment centers in Virginia, Tysons Corner and the Reston/Herndon region, as well as provide a one-seat ride from Dulles Airport to downtown Washington, DC.