Wildlife Crossing Design: Engineering Solutions for Road Mortality

Wildlife crossings including underpasses, overpasses, and culverts significantly reduce road mortality when appropriately designed and positioned for target species.

Key Facts

Road networks fragment over 70% of terrestrial land area in Europe and North America with significant wildlife mortality consequences
Wildlife crossings including ecoducts, underpasses, and culverts reduce mortality and maintain genetic connectivity
Target species behaviour determines effective crossing design, with large mammals preferring wide open crossings and amphibians requiring culverts
Banff National Park in Canada installed 41 wildlife crossings that have reduced large mammal road mortality by over 80%
Fencing that directs animals toward crossings is as important as the crossings themselves for effectiveness
Camera trap monitoring of crossing use allows effectiveness assessment and adaptive management
Amphibian tunnels under roads at regular migration crossing points have significantly reduced annual toad mortality in Europe
New road infrastructure increasingly requires wildlife crossing assessment and provision as a planning condition in some jurisdictions

Welfare Considerations

Wildlife crossing welfare is one of the clearest examples of engineering solutions to animal welfare problems caused by human infrastructure. Roads are fixed features of landscapes that will persist for decades, and their mortality impact on wildlife populations is substantial and ongoing. Wildlife crossings reduce this mortality effectively when appropriately designed and positioned, with documented reductions in large mammal mortality of over 80% in well-designed systems. The welfare benefit extends beyond mortality reduction to the maintenance of genetic connectivity that prevents the inbreeding welfare effects of small isolated populations. The challenge is retrofitting crossings to existing road networks where they are most needed, as new road planning increasingly incorporates crossing requirements. Investment in crossing retrofitting is justified by its effectiveness and by the cumulative welfare benefit to generations of wildlife in fragmented landscapes.

What You Can Do

Support organisations working on wildlife crossing installation and advocacy in your region
Advocate for wildlife crossing assessment requirements in new road and infrastructure planning
Participate in citizen science monitoring of roadkill to generate data that identifies priority crossing locations
Drive at appropriate speeds in areas with known wildlife crossing activity particularly at dawn and dusk
Support transport planning that considers wildlife connectivity as part of infrastructure design from the outset