Plan for Metro to BWI Gaining Momentum

"Whenever anybody considers expanding transit, it's something that we're always in favor of," she said. "The challenge will be whether that's something that Maryland could possibly fund."

Melissaratos said he hoped the federal government would fund as much as 90 percent of the project's cost. The rest would come from a combination of state, county and private investments.

Maryland officials said Virginia's progress on a proposed $4 billion Metro extension to Dulles has put pressure on them to speed up progress on the Green Line project.

"BWI and Dulles compete," Melissaratos said. "If there is talk about putting a Metro line in Dulles, you almost have to have one into BWI to remain competitive."

State officials said there is growing consensus that an extended Green Line -- which now ends at Greenbelt -- would have stops at BWI, Fort Meade, Laurel and a development called Konterra in Prince George's, near the future intersection of the intercounty connector and Interstate 95. Giannetti has proposed a route that would also include stations at Dorsey, Odenton Town Center and Guilford. Guilford is in Howard and Odenton is in Anne Arundel; Dorsey straddles the two counties.

"You really need Howard County's money to make this work," Giannetti said. "That's why we need a stop there."

Flanagan said the Green Line extension probably will only be the first of several links between the transit systems of Baltimore and Washington, where rapid development is transforming them into one region.

"Virginia is a perfect example of the growth occurring and them trying to catch up with it," he said. "We need to plan the growth around transit."