U.S. Transportation Secretary Ray LaHood today renewed his offer to have the Department of Transportation provide a forum for working out the region’s differences over where the new Metrorail station should be at Dulles International Airport.

LaHood was responding to a question about the future of the new Metrorail line during a discussion of national transit policy at the Brookings Institution in the District. Brookings today released a study based on extensive data showing that U.S. metropolitan areas are doing poorly at placing their transit lines where the jobs are.

The D.C. region scored very well at providing access to transit: 82 percent of working-age residents in the region live near a transit stop, compared to the national average for 100 metropolitan areas in the study of 69 percent. But despite our billions of dollars in investment in transit, resulting in one of the most extensive transit networks in the nation, only 37 percent of the D.C. region’s jobs are reachable by transit within 90 minutes. (And that’s relatively good nationwide: The average for the 100 metropolitan regions was 30 percent.)

The Dulles situation shows some of the many difficulties involved in expanding the transit network. First of all, the two-phase project will cost more than $5 billion to provide transit from its link with the Orange Line through Dulles.

Right now, the airports authority is embroiled in a dispute with local, state and federal officials over where to put the airport station. Should it be underground at the terminal, or above ground at a distance from the terminal? The difference isn’t just a matter of customer convenience. The convenience will cost $300 million more.

LaHood noted that the federal government has a $900 million investment in the project. One of LaHood’s first major actions as secretary was to sign off on the federal contribution.

He also made the offer to get the project’s stakeholders together during a speech last week to the Dulles Area Transportation Association.

He added today that he wants a solution that “respects the idea that we don’t have a bottomless pit of money.” But he again pledged that the dispute will not derail the goal of bringing the new transit line across Northern Virginia and making the airport connection.

“It’s a very important project,” LaHood said.

(I moderated an earlier panel discussion on the Brookings report, in which the panelists and I discussed the challenges that business, civic and political leaders face in extending metropolitan transit links to job sites. See The Post story on the report by Dana Hedgpeth.)