Banff National Park Wildlife Crossings — Trans-Canada Highway Mitigation Programme

Parks Canada began fencing the Trans-Canada Highway through Banff National Park and building crossing structures in 1996, after growing wildlife-vehicle collisions on the two-lane, then four-lane, highway through the park's most heavily used wildlife corridors.
The system now comprises 6 overpasses and 38 underpasses along 82km of highway, paired with wildlife fencing — the largest and longest-monitored network of its kind. Since 1996, researchers have logged more than 200,000 crossing events by 11 species of large mammal, including grizzly bear, black bear, wolf, cougar, elk, moose and deer.
Parks Canada's monitoring attributes an overall 80% drop in wildlife-vehicle collisions and mortality to the fenced crossings, rising to about 96% for elk and deer. A separate, peer-reviewed genetic study (Sawaya et al., Proceedings of the Royal Society B, 2014), based on roughly 10,000 hair samples collected at the structures, found that black and grizzly bears using the crossings interbred with bears on the opposite side of the highway — 47% of sampled black bears and 27% of grizzly bears that used crossings had successfully bred — demonstrating that the structures maintain genetic connectivity, not just physical passage.
Individual structures have cost up to CAD 4 million each, and use is uneven by species: elk and deer readily use both overpasses and underpasses, while some grizzly bears and cougars show a preference for larger, more open overpasses. Parks Canada and outside researchers consider the long monitoring record, not any single structure, the main reason the programme is cited as a global reference case.

Read the full analysis: https://parks.canada.ca/pn-np/ab/banff/nature/conservation/transport