San Francisco's New Park, Built Over a Viaduct

Nestled just south of the Golden Gate Bridge, a new section of parkland will connect the Presidio to the water. Nate Berg writes, "The Doyle Drive replacement, completed in 2015, is tucked inside concrete tunnels, the roofs of which will serve as green bridges linking the two sections of the Presidio that were separated in the 1930s." The cap park heals a physical divide that became very acute after the Presidio ceased its service as a U.S. Army base in 1994. 

According to James Corner, of James Corner Field Operations, "'When you step out on the tunnel tops, you really get a 360-degree, geographical sort of centering vantage point where you can take in every landmark and every place that's significant in San Francisco and the bay.'" Corner's firm also designed New York's High Line, which has received significant attention and praise. 

Covering freeways with parkland is an idea that has become increasingly popular nationwide. "In Dallas, for example, the 5.2‑acre Klyde Warren Park opened in 2012 on a platform over a sunken section of freeway. Los Angeles and Seattle are now considering similar freeway-cap parks."