Wallis Annenberg Wildlife Crossing

Restoring a landscape divided by infrastructure

Agoura Hills, California

Work began during Robert Rock’s tenure at Living Habitats and continues under Rock Design Associates.

The Santa Monica Mountains are home to one of Southern California’s last remaining populations of mountain lions, along with countless other wildlife species that depend on connected habitat to survive. Over time, highways and development have divided this landscape into increasingly isolated fragments.

The 101 Freeway presents one of the region’s most significant barriers. Wildlife attempting to move between habitat areas faces the danger of vehicle collisions, while animals that remain isolated experience reduced access to food, territory, and potential mates. For mountain lions in particular, this fragmentation has contributed to dangerously limited genetic diversity.

The challenge was not simply to help animals cross a road. It was to reconnect a living ecological system that had been separated by infrastructure.

The Wallis Annenberg Wildlife Crossing was conceived as a piece of living infrastructure spanning the 101 Freeway in Agoura Hills. Rather than functioning as an ordinary bridge with landscaping added on top, the crossing is designed to continue the surrounding habitat across the freeway.

Its development brings together decades of scientific research, ecological planning, advocacy, engineering, and landscape design. Rock has directed the design since 2019, working closely with Caltrans District 7 on the final engineering documents and overseeing the project through construction.

RDA’s role has also included collaboration with scientists, researchers, academic partners, and the broader project team so that decisions about soils, planting, wildlife movement, screening, and infrastructure performance are informed by the best available knowledge.

Response for Wallis Annenberg Wildlife Crossing

The crossing represents more than a safe passage over a freeway. It is an effort to restore ecological continuity across the Santa Monica Mountains and create connected habitat for mountain lions and the many other species that move through this landscape.

The story of P-22 helped bring international attention to the consequences of habitat fragmentation. After crossing major freeways and making his home in Griffith Park, he became a symbol of both wildlife resilience and the urgent need for safer movement through the region.

The Wallis Annenberg Wildlife Crossing carries that legacy forward. It demonstrates how infrastructure can serve human mobility while also repairing ecological connections—offering a hopeful model for how design, science, and collaboration can help people and wildlife share the landscape.

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A landscape reconnected

The Wallis Annenberg Wildlife Crossing is designed not simply as a bridge, but as an extension of the Santa Monica Mountains themselves. Native soils, carefully selected plant communities, natural screening, and varied terrain work together to create habitat that feels continuous rather than constructed.

Every element supports movement across the freeway while reducing the sights, sounds, and disturbance of traffic below. The result is living infrastructure shaped by ecology—creating a safer passage for wildlife and restoring a connection that the landscape has been missing for generations.

More than a crossing

The Wallis Annenberg Wildlife Crossing represents what becomes possible when science, design, engineering, advocacy, and public support move toward a shared goal. It restores a vital connection across one of Southern California’s most significant barriers while creating a model for how infrastructure can respond more thoughtfully to the natural systems around it.

For Rock Design Associates, the project reflects a long-term commitment to collaboration, ecological understanding, and design that serves both people and place. More than a passage over a freeway, the crossing is a lasting investment in the resilience of the Santa Monica Mountains and the wildlife communities that depend on them.