The Obama administration has contributed $900 million to the first phase of the Silver Line, which will run on existing Metro tracks in Prince George's County, Md., and Washington before transitioning to 11.5 miles of new tracks that will lead to Reston, Va. Another 11.5 miles, which will include a station at Dulles airport, are expected to be constructed by 2018.
LaHood said the Silver Line project would ease traffic congestion in northern Virginia's populous Tysons Corner area.
"The extension will serve Tysons Corner, Virginia's largest employment center, and the Reston-Herndon area, the state's second largest employment concentration," he said. "And it will provide a one-seat ride from Dulles International Airport to downtown Washington."
LaHood said the new Metro line was necessary because "[C]urrently, Tysons Corner functions like a suburban city, with a population that quadruples during the workday.
"Local leaders hope to attract more people to live in Tysons Corner in addition to just working there," he wrote. "Plans are underway to urbanize Tysons Corner by adding multiple modes of transit, bike lanes, pedestrian-friendly streets, and a robust mix of uses."
LaHood added that the Silver Line would help Tysons.
"The Silver Line will help Tysons Corner, and it will also help preserve the rural nature of western Loudoun County by absorbing growth in higher density development around the two stations in the eastern part of that county," he wrote.
Construction of the first half of the Silver Line is expected to be completed by August 2013. WMATA has said the agency will have to test the new stations and track, which are being built by the panel that oversees Washington's regional airports, before it begins carrying passengers on the new route.