What you imagined do exist. They use them to allow animals to migrate across highways without putting them in danger. See this: https://www.canadiangeographic.

What you imagined do exist. They use them to allow animals to migrate across highways without putting them in danger. See this: https://www.canadiangeographic.ca/article/banffs-famed-wildlife-overpasses-turn-20-world-looks-canada-conservation-inspiration https://www.canadiangeographic.ca/article/banffs-famed-wildl...