Abstract

The international green infrastructure literature has examined rails-to-trails and freeway-to-boulevard conversions, but these strategies can be impractical or politically unfeasible. An understudied movement among United States cities has demonstrated a strategy for greening freeways that remain in service: freeway cap parks, or decks with parks built in the air space directly above below-grade freeway sections that can help reintegrate communities, conceal traffic, reduce air pollution, and provide green space. We provide the first assessment of the design, function, and placement of freeway cap parks and assess the emerging sustainability discourse of cap park planning. We examine 18 completed and 9 proposed cap parks in 24 U.S. cities to identify four cap park development models that can be adapted worldwide to green below-grade freeway segments and reconnect communities. Given historic disparities in freeway placement, we examined the distribution of cap parks and found they are located in areas that could help address disparities in park access in freeways corridors. Our detailed case studies stress the struggle within the cap park sustainability discourse to balance economic, environmental, and equity concerns. Dallas’ Klyde Warren Park is an economic success story, but illustrates how developers use cap parks to sideline equity concerns. Denver’s proposed I-70 cap park illustrates strategies to mitigate environmental justice impacts of freeway expansion projects, but equity concerns remain given continuing impacts of the expanded freeway system. Cap parks should be embraced as a vital component of green infrastructure that reconnects and greens cities divided by freeway construction, but planners should take strong steps to address housing affordability and gentrification concerns for adjacent communities.