Das Val Müstair kennt schon Tunnels für die Skifahrer. Wieso bei der Umfahrung von Sta.Maria nicht ein Tunnel für die Bären bauen?

Just as a driver never knows which way a deer in the headlights will jump, a study of Highway 93’s wildlife fencing project produced some unpredicted results.
For example, the place where most deer turn into roadkill isn’t always the best place to build a crossing structure. And the usefulness of an animal underpass depends on how long we build the fence beside it.

As more and more roads cut across the territories of wild animals, wildlife crossings are being built to bridge these barriers. But there has been little evidence that animals actually use the crossings.
Now, a team of researchers at Montana State University has compared the genetics of grizzly bears and black bears at road crossings in the Canadian Rockies, finding the bears do indeed move across the Trans-Canada Highway, and breed with mates on the other side.
https://www.livescience.com/43467-black-bears-and-grizzlies-use-road-crossings.html

Paul Marangelo parked his rusty Honda on the side of Route 15 in Wolcott and headed toward the bridge over the Wild Branch, a scenic tributary of the Lamoille River. The Nature Conservancy biologist was out to see whether animals were using the riverbank to travel beneath the busy highway.
Tunnels for small animals are appropriate where a road or railway line across natural areas is built on an embankment. However, they can also be built where the transport infrastructure lies at surface level.