Wildlife crossing structures — tunnels, bridges, and culverts — dramatically reduce road mortality and restore habitat connectivity, with strong evidence for effectiveness across many species.
Road mortality imposes acute welfare costs — traumatic injury and death — on millions of animals annually. Surviving collision animals may suffer for hours before death or discovery. Wildlife crossing infrastructure prevents this harm while also restoring gene flow between fragmented populations. Effectiveness depends on design appropriate to the target species, habitat quality at crossing entrances, and fencing that guides animals toward crossings rather than along road verges. The cost of crossing infrastructure is typically recovered within years through reduced vehicle damage and human injury from collisions.