A rendering shows an example of what the cap park, covering the Connecticut Avenue underpass just north of Dupont Circle, could look like. ( Hunt Laudi Studio)

The District’s capital budget for fiscal 2015, which begins in October, includes $10 million to build a pedestrian deck over the Connecticut Avenue underpass just north of Dupont Circle. But don’t expect to stroll directly from Kramerbooks & Afterwords to Shophouse Southeast Asian Kitchen anytime soon.

“I think we’d be lucky if it took three years,” said Mike Feldstein, the advisory neighborhood commissioner who has thus far shepherded the proposal for what’s being called the “cap park.” The new plaza over what is now thin air, he estimates, will be about 15,000 square feet.

“The problem isn’t the construction, I don’t think,” he said. “It just requires all kinds of studies and analysis and things like that. Much more so than I had realized.”

The project is the responsibility of the city’s Transportation Department, said Tom Lipinsky, director of communications for Ward 2 Council member Jack Evans, who represents the neighborhood.

“I think the plan is to begin the design process concurrent with the covering, or in advance of the covering,” he said. “It’s not just cover it, and then we wait a year while we’re submitting designs or deciding on designs.”

The $10 million will fund a plaza over the underpass between the circle and Q Street, Lipinsky said, “and a little bit more as well.” The additional decking will take the park part of the way to R Street, where the avenue’s submerged lanes return to the surface.

“We want to have a place where somebody can actually sit down and maybe order a glass of wine. That’s unheard of [in a city park] in Washington, D.C., or the United States,” Feldstein said. “And if we have concessions like that, then it begins to pay for the upkeep and maintenance.”

The cap park, Feldstein suggested, could be a new home for Sunday’s Fresh Farm market, which currently closes the adjacent block of 20th Street for much of the year.

Choosing a design for the park, he said, “will be a combination of a competition and representatives from the community. I think the trick is not starting something too quickly, but rather benefiting from learning what’s worked in other places.”

One group that’s watching the design process closely is the Arts Coalition for the Dupont Underground, which is working on plans to redo the other passageways under the circle: the streetcar tunnels that have been largely unused since trains stopped running in 1962. Much of the subterranean space would be devoted to exhibitions and events, but additional uses are possible.

“This is potentially a huge game-changer for Dupont Circle,” said Braulio Agnese, the arts coalition’s managing director, who estimates the deck would be between 5,000 and 6,000 square feet.

“The cap park is something that we’ve been advocating for years,” he said. “We’re really excited that this is finally getting attention and things are going to begin happening. We just want to see them happen in a coordinated way, and in the best way possible for the neighborhood.”

The arts organization hopes to coordinate its remaking of the streetcar tunnels with the decking of the overpass, in part to minimize construction disruption in the neighborhood. “The work on the cap park may affect our plans,” Agnese said. “We can’t be making plans for something to be happening in three or four years if in three or four years that part of the space is not going to be available.”

Beyond that, the projects might synchronize in other ways, he said. “For instance, we’ve gotten proposals to turn part of the tunnel into a hydroponic farm, an underground terrarium space to grow vegetables or who knows what. Why couldn’t the cap park be a rain collector, say, to help feed that?”

Agnese said he and his colleagues support a design competition “to bring out the best ideas.” Hunt Laudi Studios, a Dupont Circle architecture firm whose principals include arts coalition founder Julian Hunt, has proposed an undulating, green-roofed pavilion for the plaza.

“We’re just trying to get that conversation underway,” Agnese said. “We would like to see this process done thoughtfully . . . and with an eye toward permanence.”

“This is a really great opportunity for the neighborhood, and it would be a shame if it were botched just because somebody wanted to get it up in a hurry.”

Jenkins is a freelance writer.