California, the world’s largest overpass to save Hollywood P-22 pumas

Just outside of Los Angeles, about twenty minutes from Malibu, runs a ten-lane section of Highway 101, one of the busiest in the country with over 300,000 vehicles passing through daily. It represents the biggest obstacle for the natural habitat of local wildlife. For Californians, it’s “the highway to hell“. And the same would be said, if they had the gift of speech, by the wild animals that inhabit the Santa Monica Mountains, including 400 species of birds, 50 of reptiles, and 46 of mammals. The wildlife in those parts includes at least 50 endangered species. It has an official representative: the mountain lions, once classified by the National Park Service with the code P-22 pumas. Famous for making Griffith Park its home and for being photographed right in front of the iconic Hollywood sign overlooking Los Angeles, the puma was euthanized in December 2022 after being injured by collisions with vehicles during its crossings of Highway 101. Since then, California has mobilized to prevent similar incidents, given the increase in traffic and wildlife crossings of the highway.

In the Liberty Canyon area of Agoura Hills, at the foot of the Santa Monica Mountains, the largest wildlife bridge in the world is being constructed, dedicated exclusively to wildlife crossings and will be 210 feet (64 meters) long. California Governor Gavin Newsom celebrated the placement of the first of 82 large concrete beams of this infrastructure last June and announced that the work would be completed by 2026. The infrastructure is not unique, as there are similar ones in many U.S. states and other countries like Australia, Canada, Israel, and the Netherlands, which has over 600. But in terms of size and cost, nearly $100 million, the overpass on Highway 101 is undoubtedly the largest overpass in the world.

The project is the result of a public-private partnership funded with $58.1 million from the state of California and an additional $34 million from a fundraising campaign launched by philanthropist Wallis Hubert Annenberg. In her honor, the new crossing will be named “Wallis Annenberg Wildlife Crossing,” although social media has already dubbed it “The Hollywood Cat Crossing.”

According to official statistics, in the U.S., road crossings result in over a million large animal casualties annually, the deaths of over 200 people, and the injury of another 26,000 drivers and passengers. In the case of accidents without casualties, the average insurance cost is about $4,500, amounting to billions in damages annually. Over the past decade, overpasses or underpasses have multiplied, dedicated, depending on the area, to bears, wolves, raccoons, armadillos, deer, elk, alligators, lizards, and even butterflies to prevent them from hitting car windshields. These infrastructures are covered with vegetation and soil to make them more akin to the wildlife habitat and are usually off-limits to people.

According to university estimates, these safe crossings reduce accidents by over 80% annually. Washington State University has published research indicating that wildlife crossings are a good deal for the community, considering that the average one-time cost is around $4-6 million, and the economic savings in terms of avoided collisions can exceed $500,000 annually. Therefore, their use in America is in full development, so much so that the Federal Highway Administration has published a comprehensive manual for builders on its website, the “Wildlife Crossing Structure Handbook Design and Evaluation in North America.”