A closer look
You might assume a grizzly bear would just blindly wander across a highway, but they are actually incredibly paranoid about exposed, unnatural infrastructure. When engineers built barren concrete bridges over the Trans-Canada highway, the bears flatly refused to use them. It wasn't until ecologists covered the bridges in thick, native vegetation, built sightline-blocking berms, and placed them in natural topographic funnels that the bears finally felt secure enough to walk directly over thousands of screaming semi-trucks.
