Through the center of Dallas, Texas, runs the Woodall Rodgers Freeway-a gash of below-grade, multilane concrete that divides this southwestern metropolis. It's a situation found in most American cities where, for decades now, highways have hung like nooses around urban centers, choking off one part of a city from another and disrupting community life.
But that's about to change. In November 2009, Dallas began constructing a deck over the freeway that will support a 5.2-acre park. Upon completion in 2012, the yet-to-be-named deck park will reconnect uptown and downtown for the first time in decades, and provide a majestic green centerpiece for the city's burgeoning art district. With noisy traffic disappearing under the park's cover, Dallas will take a big step toward becoming a more walkable, pedestrian-friendly city.
Building a park over a city highway is not a new phenomenon. In 1939, Robert Moses reconstructed the 14-acre Carl Schurz Park and placed it on top of the Franklin D. Roosevelt Expressway along Manhattan's East River. Moses did it again in 1950, this time in response to public backlash against his plans for an expressway through the heart of Brooklyn Heights. Instead, he decked the highway over with the Brooklyn Promenade, a leafy park overlooking lower Manhattan.
More recently, parks over highways have appeared in Boston, Phoenix, Seattle, Trenton, N.J., and Duluth, Minn., to name a few places. Peter Harnik, director of the Center for City Park Excellence at the Trust for Public Land, called Margaret T. Hance Park in Phoenix a model of a successful urban deck park, one which knits together a once divided section of the city and muffles the noise of cars and trucks below. "They built a library and Japanese park on top," Harnik says, "with the result that it attracted development of 10-story condos."
Despite the bad economy, interest in deck parks has only grown stronger, according to Harnik. Cincinnati, Los Angeles, St. Louis and Santa Monica, Calif., are either proposing or planning to cover up highways with green space. They work best where highways are built below grade, making them easy to deck over to unify a divided city or provide a link to a waterfront as the deck parks in Duluth and Brooklyn do.
Yes, Harnik admits, they are expensive -- the Dallas deck park will cost $100 million in public and private funds -- but the land is usually free and the value of having a new downtown park is immeasurable. Plus, the value goes right to the edge of the park, where developers are eager to build housing that overlooks an oasis of green in the middle of the city.
Harnik, who has written extensively about parks over highways, says the key to a successful highway park is the economic impact. "With a deck costing as much as $500 per square foot to build, it must be carefully justified through its potential as a redevelopment tool for surrounding real estate," he writes in his book, Urban Green. "Only then will the rate of return show both public and private funding sources the value of the investment."