[This post has been updated]

The board of the Metropolitan Washington Airports Authority, which operates both Dulles and Reagan National, as well as supervises the construction of of the new Metrorail line to Loudoun County, approved a funding deal Wednesday for Phase 2 of the subway extension.

Secretary of Transportation Ray LaHood announced last week that a financing deal was in place, although the agreement still needed the approval of the governing boards of the jurisdictions involved, including Fairfax and Loudoun counties and the airports authority, which gave its okay during a board meeting Wednesday.

LaHood said the federal government will provide loan assistance and Virginia has agreed to provide $150 million for the $2.8 billion second phase.

Board member Tom Davis said during the meeting that there are “a lot of land mines ahead” in Phase 2 of the project, meaning higher fees for Dulles Toll Road users and higher subsidies from the jurisdictions. Percentages of the costs are being contributed by jurisdictions, with toll revenue making up the largest portion.

The rail line will eventually stretch 23 miles from Falls Church to Loudoun County. The first segment is under construction through Tysons Corner to Reston and is scheduled to open in 2013. The airports authority will turn over the line to Metro to operate and maintain as part of its regional rail system.

Follow Dana on Twitter @postmetrogirl, or peruse her tweets from the meeting below.

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