A 150-foot land bridge spanning a six-lane highway has become the unlikely centerpiece of a prairie restoration effort in San Antonio, Texas. The Robert LB Tobin bridge, constructed at Phil Hardberger Park, serves dual purpose: animals ranging from deer and coyotes to bobcats cross safely overhead while pedestrians use the same structure to traverse what was once an impassable barrier.
The park itself covers 311 acres of what was formerly a dairy farm, now reclaimed as native Texas prairie. That ecosystem is nearly extinct in North America, with only about 1% of the original prairie remaining. The design team at Stimson Studio and Rialto Studio devoted 75% of the park to prairie restoration, leaving 25% for visitor amenities including an urban ecology center and parking areas.
The challenge was unavoidable: a freeway cut directly through the center of the open space, fragmenting habitat and creating a natural boundary that prevented wildlife movement. Taking inspiration from European wildlife crossing designs, the architects conceived a bridge that would function as a seamless extension of the landscape rather than an obvious infrastructure project.
What makes the bridge work ecologically relies on careful separation of human and animal spaces. Pedestrian walkways occupy one side of the 150-foot width, while the opposite side remains dedicated to wildlife movement. An elevated berm and strategic plantings buffer the two zones from one another. Eight-foot steel walls block views of the highway and shield animals from headlights and engine noise.
The bridge opened in 2020. Within six months, wildlife biologists documented coyotes, deer, bobcats and small mammals using the crossing. The park has since become a stopover for migratory birds, with conservationists tallying more than 180 different species, including Nashville warblers and various other migrants.
The site also draws visitors through eight miles of winding trails lined with mature oak trees, including one specimen over 400 years old. Native wildflowers dot the landscape, from magenta Texas thistles to yellow creeping oxeye. Local artists designed viewing sheds scattered throughout the park, providing quiet resting spots where visitors can observe wildlife without disrupting it.
Phil Hardberger, the former San Antonio mayor who served from 2005 to 2009, championed the project as part of a broader platform focused on quality of life. Political advisers had warned him that emphasizing parks and beauty would not generate votes, but Hardberger sensed voters cared deeply about livability and amenities beyond raw economic growth.
Temperature on the bridge runs a few degrees warmer than surrounding prairie due to heat-absorbing materials like stone and metal, combined with younger plantings that produce less cooling evapotranspiration than the established oak savanna. Circular cutouts integrated into the design provide necessary airflow to prevent excessive heat buildup.
Gregory Tuzzolo, an associate principal at Stimson Studio, emphasizes that the bridge solves a fundamental ecological problem. Creating isolated parks and conservation zones means little if wildlife cannot move between them. A landscape fragmented by highways remains degraded even with protected spaces on either side. The bridge restores connectivity that highways had severed, allowing ecological function to resume across the divided terrain.
Author James Rodriguez: "This isn't just feel-good environmentalism, it's a direct answer to a problem highways create everywhere, and San Antonio actually built it."
Comments