More Than Human: A Land Bridge for Cultural and Wildlife Connections by STIMSON

Phil Hardberger Park, is a 330-acre urban park in San Antonio, the 7th largest city in the United States. Designed in phases from 2007-2019, the park opened to the public in 2010 as a cultivated wild, where trails wind through preserved woodlands and restored savanna, with parking, picnic and play carved from scrubland. For over a decade, the park existed as two parcels and the last piece of the Comprehensive Plan, the land bridge, remained unrealized. Six lanes of Wurzbach Parkway severed the landscape, creating a barrier for humans and causing fatal collisions for wildlife migrating along the 38-mile-long Salado Creek. The land bridge was finally realized through a 2017 voter-approved city bond of $13 million and $10 million in grants and donations. It opened to the public in December 2020 and the park sustains 750-1,000 visitors per day. The project demonstrates a union of urban wildness and city-wide activism.

The bridge was conceived as a flowing extension of the land itself. Sculpted earth, layered with amplified savanna and scrubland, spans 175’ across Wurzbach Parkway and reconnects both sides of the park back to Salado Creek. The 160’ wide corridor of densely planted landscape is bermed along one edge for wildlife movement, while offering a narrower, accessible trail system for people. A 25 foot elevated skywalk of wood and steel sensitively winds through the tree canopy to the top of the land bridge. At the summit, steel parapet bridge walls create unexpected quietness, and the view extends for miles across the city. Wildlife blinds are sited at either end of the bridge, offering shade and a chance to observe animals at the water guzzlers. The perforated wall patterns take cues from the site’s flora and fauna, created by local artists and detailed by the landscape architects. All the materials, plants and forms of the bridge are responsive to the site and inspired by the region.
At over 20 acres, the project reused site soils and 120,000 cubic yards of earth, and recycled tons of cleared brush as mulch. Resting on 16 arched girders that stretch across the highway in a single span, there are no support columns and the structure’s bowed cross section and steel walls provide site and sound barriers from traffic below. Locally quarried limestone forms abutment walls that feather back into the planted slopes. Girders were craned into place at night to avoid road closures and the single span avoided highway repaving. Rainwater is collected in a 1-acre wetland that doubles as a wildlife watering hole. A 250,000-gallon underground cistern harvests rainwater, providing irrigation through San Antonio’s droughts.

Wildlife biologists educated decisions on bridge dimensions and habitat requirements to maximize animal crossings. Passage is guided by 3,300 linear feet of barrier fencing along Wurzbach, directing animals upwards, while berms and plantings provide continuous cover across the structure. The bridge diversifies habitat with over 50 reintroduced species, many bearing fruits, providing shelter and supporting prey species. Before the first anniversary of the bridge, every mammal species known to reside within the park was captured on the land bridge’s trail cameras, including bobcat, white-tailed deer and ringtail cat.

The Robert L.B. Tobin Land Bridge demonstrates the ability of a landscape architect-led team to conceive and design large-scale, contextual infrastructure that prioritizes wildness in the urban realm.

• All landscape architecture offices involved in the design of landscape: STIMSON and Rialto Studio

• Other credits:
ARUP (Structural Engineer), SWCA Environmental Consultants (Wildlife Biology), Cude Engineering (Civil Engineering), Ashley Mireles (Artist, collaborator on wildlife blind), Cade Bradshaw (Artist, collaborator on wildlife blind)