The beleaguered airports authority in charge of the $6 billion Dulles Rail project on Wednesday agreed to give the nation's top transportation official broader oversight powers to monitor the authority's recovery from a series of ethical and contracting scandals.

The Metropolitan Washington Airports Authority voted to allow U.S. Transportation Secretary Ray LaHood "full access at any time" to the authority's "books, records, contracts, and documents." The new agreement also gives LaHood veto power over any future changes made to the authority's new ethics policy.

The authority is being forced to accept federal oversight after a scathing inspector general's report last month found an ongoing "culture of favoritism" at the agency, including insider deals, no-bid contracts and nepotism. The agency has since revised many of its policies.

Authority Chairman Michael Curto said the authority will ask LaHood to limit the how long the federal government would have oversight of the authority.

Authority member Warner Sessions, a D.C. representative on the regional board, was the only board member to vote against allowing federal oversight, though his spokesman said Sessions' concerns "were of a mechanical and legal nature."

The authority on Wednesday also changed a lease agreement to give it the authority to develop land at Washington Dulles International Airport, possibly for a conference center and other buildings that would be convenient to the new Dulles Metrorail line. Dulles has 3,000 acres of land it isn't using, officials said.

"Obviously the land around a train station has a lot of value. ... Right now we're just in the talking stage," Authority CEO Jack Potter said. "[A conference center] is one of the alternatives. There are many alternatives out there."

Airlines at Dulles would help pay for the infrastructure on the development site, so any money made on the development deal would go to the airports, Potter said. The money can't be used to pay for Metrorail's new line to Dulles -- and reduce the Dulles Toll Road fees that will pay for most of that rail line -- since it comes from the airlines.

But Authority board member Tom Davis said toll road drivers may still benefit from the airports' development deals.

"Even helping the airport indirectly -- I'm not saying money's fungible -- it helps alleviate overhead costs and structure on your debt," Davis said. "This is right on the rail line, so we may have some way we can relieve the rail line."

Virginia Gov. Bob McDonnell and D.C. Mayor Vincent Gray must still sign off on the changes.