Transportation experts say Metro will be hard-pressed to fund any of the projects included in a $26 billion wish list for an expansion of the transit system.
The agency's strategic plan includes new rail tunnels, bus-only lanes and streetcars across the Potomac River, with officials saying it needs a major expansion to keep up with growing demand.
But Ron Kirby, director of transportation planning for the Metropolitan Washington Council of Governments, pointed out that Metro has had extensive plans in the past that have never been completed.
"In the past, there have been incredibly grand proposals for new tunnels and things like that, which are so costly they get put on the back burner," Kirby said, adding that parts of the new plan -- such as eight-car trains -- have a better chance.
But two new tunnels, each costing about $3 billion, through Georgetown and downtown D.C., have "absolutely no possible prospect of funding," Kirby said. "You'll have to come up with a whole other way to fund these things."
In addition to the new tunnels, both of which would go under the Potomac River, Metro by 2040 wants $1.9 billion worth of streetcars crisscrossing the District and Northern Virginia, and the Orange and Silver Lines extending to a second Pentagon station for a price tag of $2.9 billion.
"These are the investments that we need to make today so that Metro can catch up with the growth that's already happened," said planner Shyam Kannan. "The cost of not doing this is immense."
By 12 years from now, Metro's plan calls for $2 billion for running only eight-car trains -- instead of a combination of eight- and six-car trains -- $600 million for creating bus-only lanes for busy commuter corridors and $1 billion for two pedestrian tunnels between busy downtown stations, among other items.
But scraping together billions of dollars for Washington transit will be tough when politicians in Maryland and Virginia are struggling to find funds for basic road maintenance, and the federal government is cutting everywhere.
"If anything, federal [transportation] funding at best is stagnant and is potentially going to decline," said Joshua Schank, president and CEO of the think tank Eno Center for Transportation. "I think that the price tag [for the Metro plan] is such that it will have to be modified if it's going to be successful."
The current political climate could be fatal for Metro's plan, experts said, though they said it was good for Metro to plan for the future.
"A lot of [this plan] catches up to things we ought to have been doing 10, 20 years ago," said local transit advocate David Alpert. "The current dynamic in transportation is that regions generally and states and the federal government aren't really willing to fund transportation."