This is an excerpt from our package of articles about what Washington will look like over the next few decades. For the full package, see our April 2015 issue—on newsstands now, or purchase the digital edition optimized for your tablet here—and come back to the website for more stories over the next few weeks.

Underground Mall

A panacea for parking shortages, bus traffic, fossil-fuel burning, and flooding tucked beneath the Mall? That’s what a proposed parking garage—buried under the grassy expanse between the National Museum of Natural History and the Smithsonian “Castle”—purports to be. The multilevel space could accommodate 900 cars and 200 buses, in addition to a central visitor center and public restrooms. A 34-million-gallon overflow reservoir would prevent a repeat of the flooding that swamped Federal Triangle in 2006. And, rain or shine, more than 1,000 geothermal walls beneath the garage would harvest energy to heat and cool nearby museums and government buildings. It might sound too good to be true, but acclaimed Washington architect Arthur Cotton Moore is spearheading the initiative, lending significant credibility to it.

Up in the Air

Rendering courtesy Georgetown BID.

It might seem far-fetched that gondolas—typically for ferrying powder hounds up ski slopes, not yuppies across the Potomac—could solve Georgetown’s public-transit deficit, but apparently not to the folks at the Georgetown Business Improvement District. Their proposal calls for a dangling, four-minute cable-car connection to and from Rosslyn. Costs have yet to be projected.

The New WMATA Map

Map illustration by Todd Detwiler.

Four big plans to extend Metrorail.

Orange Line Extension

The Orange Line is overdue to expand service to neglected hubs like Fairfax, Centreville, and Manassas. But stretching the route could worsen its infamous “Orange crush” overcrowding, and with Metro’s attention elsewhere, the project has no set timeline.

Silver Line

If all goes as planned, by 2050 this line will have been running to Dulles for 32 years and will serve stops as far out as Ashburn.

Purple Line

With a $2.4-billion price, the light-rail line running through Montgomery and Prince George’s counties faces a skeptical governor in Larry Hogan, but momentum, public opinion, and a projected 70,000 daily riders could make it a reality as early as 2020.

Georgetown Tunnel and Inner Loop

WMATA wants to dig a tunnel under the Potomac, serving stops at Georgetown University and the neighborhood’s shopping district. It would connect to a new inner loop running through ten stations around the heart of DC, in spots including the West End, Thomas Circle, and Potomac Park. At an estimated $26 billion, it’s not cheap, but a line designed to circulate riders around the city, rather than take them in and out of it, would be a game-changer.

Project Runway

In 1962, Dulles’s first year of operation, 53,000 passengers traveled through the airport. Though passenger numbers have recently declined there while Reagan National has gained popularity, there are still 20 million who pass through Dulles every year—and unlike Reagan, Dulles is in the unique position of being able to add another 10,500 feet of tarmac. Demographers say the lag there won’t last forever and that as our population grows, it’s only a matter of time before Dulles adds a fifth runway.

Need for High Speed

Rendering courtesy Amtrak.

Amtrak’s $7-billion proposal to overhaul Union Station includes six tracks for high-speed rail that could shuttle passengers to New York in about an hour and a half—much faster than the nearly three-hour trip on Acela but not nearly as fast as the pitch from the Northeast Maglev. That company is pushing a maglev (magnetic levitation) train—which floats above a magnetic track—that would cut a DC-to-Baltimore commute to 15 minutes and a DC-to-New York journey to an hour. The biggest hurdle is cost: In 2007, a proposed maglev line between just Camden Yards, BWI, and Union Station was estimated at $5.1 billion. High-speed rail is inevitable for Washington—just how high-speed is still unknown.

Bridge-Building

Photograph by Flickr user Beyond DC

The only way to drive across the Potomac between Montgomery County and Fairfax and Loudoun counties is via the often bumper-to-bumper American Legion Bridge. A new span across the river, with a highway extension, would alleviate congestion. Maryland governor Larry Hogan has a professed affinity for road-building, but odds are split it happens by 2050.

Don’t Miss Another Big Story—Get Our Weekend Newsletter Our most popular stories of the week, sent every Saturday. Or, see all of our newsletters. By signing up, you agree to our terms