The proposed park that would snake atop Ga. 400 in Buckhead’s business district is part of a nationwide highway-capping trend that has created green spaces from Seattle to Boston and from Chicago to Dallas.

The reason is simple: Highway-capping can be a relatively easy way for a city to gain green space. But the challenge is big: Costs can be high and piecing together the public-private partnerships typically involved is complicated.

The East Lawn of Klyde Warren Park in Dallas. (Office of James Burnett)

“The most important piece of advice I give a community like Atlanta that is considering [a cap park] like this is, find your champion,” said Tara Green, president of Klyde Warren Park in Dallas, which has become a model of highway-capping success.

Klyde Warren Park’s champion was banker Jody Grant, “who didn’t take no for an answer” and put up $1 million of his own money to start leveraging public financing for the $110 million project, Green said.

For the Buckhead Community Improvement District board, which has proposed the park, costs have been a concern. The current proposal is not a complete cap, but rather a large bridge paralleling Ga. 400, partly because that is easier to build.

After a project gets a champion, keeping the price tag reasonable can be another challenge. Boston’s downtown has been reconnected with the 1.5-mile Rose Fitzgerald Kennedy Greenway, built atop a formerly elevated highway now sunken in a tunnel. That project, nicknamed the Big Dig, became notoriously wasteful, with cost estimates running well over $15 billion.

However, now that it’s complete, Boston’s Greenway is extremely popular, packed with public art and events, according to Janet Knott, the policy and media director for Boston City Councilor Sal LaMattina, whose district includes much of the park. Like Buckhead’s proposal, the Greenway has sub-parks in different sections.

The North End Park section of Boston’s Rose Fitzgerald Kennedy Greenway. (Special)

“It’s a set of parks defined by the neighborhoods along it,” Knott said. “It involves the neighborhoods by creating this network instead of creating this blanket open space.”

“This [park over Ga. 400 idea] is exciting for your city because, as you know, parks are so popular all over the country,” Knott said. “Trying to find green space is a priority for many cities right now.”

Just as carving highways through city centers was popular in the 1950s and ’60s, cap parks are a modern urban planning trend. An early example is Seattle’s Freeway Park, built in the 1970s. St. Louis has a cap park underway, part of a renovation of its Gateway Arch monument. And such major cities as Chicago and Los Angeles have highway-cap parks on their drawing boards. The Buckhead CID’s concept isn’t even the only one in Atlanta, as Central Atlanta Progress is proposing a Downtown Connector cap called the “Stitch,” which would include both park space and buildings.

Earlier this year, various Atlanta leaders, including Buckhead CID Executive Director Jim Durrett, visited Dallas to hear about Klyde Warren Park, which opened in 2012 and now draws a million visitors a year—significantly more than expected.

Green said that what Dallas’s plan had, besides a champion, was civic motivation. She said there is some evidence that “city leaders knew they were creating a moat” with the highway in the 1960s and had early ideas of bridging it somehow, making the city more receptive to the park idea. But the real “catalyst,” she said, came in 2001, when the giant aircraft corporation Boeing chose Chicago over Dallas for its new headquarters. A main reason Boeing cited for rejected Dallas was the lack of a “vibrant downtown,” she said.

Klyde Warren Park in Dallas. (Office of James Burnett)

Like Atlanta, Dallas is a city of infamous sprawl, endless highways and relatively little green space. Klyde Warren Park became a place to move away from car culture and provide a “back yard” to people increasingly living downtown, Green said, echoing concerns of Buckhead’s leaders.

“We did not have that reason to walk in Dallas,” she said. “We’re so happy we have taught Dallas how to walk.”

The park is city-owned, but privately run and managed, including private security. It is self-funded, using no city park funds, Green said.

The Dallas park’s success comes with some wrinkles. According to media reports, most fundraising targeted the park rather than the less glamorous cap structure. The park is so popular the administration is already considering an addition, including a controversial parking garage.

Still, Green has a simple message for Buckhead’s park planners: “It will be well worth the investment.”

Major U.S. highway-cap parks

Rose Fitzgerald Kennedy Greenway

Boston, Mass.; opened 2008

15-acre, 1.5-mile-long park atop a highway tunnel. Cost more than $15 billion, including all of the Big Dig.

Klyde Warren Park

Dallas; opened 2012

5-acre cap over a highway that was already built below-grade. Cost $110 million. In August, proposed a $90 million addition that would include restaurant, park offices, many amenities and a parking garage.

Margaret T. Hance Park

Phoenix, Az.; opened 1992

32-acre park built atop a highway tunnel at a cost reportedly over $100 million. Plans for a $118 million renovation/redevelopment are in the works.

Freeway Park

Seattle; opened 1976

5-acre cap over a highway.