Wildlife Crossing Infrastructure: Engineering Solutions for Animal Welfare

Wildlife crossings allow animals to move safely through human-fragmented landscapes. Engineering solutions at this intersection of infrastructure and ecology reduce animal suffering at scale.

Key Facts

Over 600 wildlife crossings have been built in the US — results show dramatic reductions in road mortality
The Wallis Annenberg Wildlife Crossing in Southern California cost 87 million USD to build over a 10-lane highway
Wildlife underpasses and culverts are significantly cheaper than overpasses but effective for many species
Camera trap monitoring of wildlife crossings shows usage by large mammals within weeks to months of opening
Smaller crossings including amphibian tunnels allow seasonal migrations of frogs and newts that would otherwise be decimated
Wildlife crossing design must account for species-specific behavior — some species will not use poorly designed structures
Transportation departments that incorporate wildlife crossing standards into standard highway design dramatically reduce wildlife mortality

Welfare Considerations

Wildlife crossing infrastructure addresses animal welfare at a scale that individual advocacy cannot match. A single well-placed wildlife crossing prevents hundreds or thousands of vehicle collisions annually, preventing both acute trauma from collision and the prolonged suffering of injured animals unable to seek help. The mountain lion population in the Santa Monica Mountains — isolated without the Wallis Annenberg crossing — faced extinction from inbreeding depression within decades. The crossing addresses both population-level welfare through genetic rescue and individual welfare through collision prevention. Transportation infrastructure decisions are political — they require sustained advocacy to incorporate wildlife crossing standards. But the welfare return on investment is enormous and the science is unambiguous.

What You Can Do

Advocate for wildlife crossing standards to be incorporated into highway design requirements in your jurisdiction
Support local campaigns for specific crossings in areas with documented high wildlife road mortality
Donate to organizations including Center for Large Landscape Conservation working on crossing policy and funding
Engage with transportation departments to include wildlife welfare in environmental impact assessments
Support Safe Passages programs that identify and prioritize crossing locations using mortality data