My guess is that it will be a “nature highway” so migratory species can cross over the road

These are great for wildlife as they provide a safe crossing over high-speed highways. They are usually design to be in already existing migration paths where moving a proposed highway may not work and not disrupting migration paths is of importance.

Looks like a nice choke point for a predator to hang about.

Are there any predators smart enough to strategize like this? I know that some use water holes as hunting grounds, but that’s probably more instinctive than actual strategy.

Are there any predators smart enough to strategize like this?

it is the predators that build such passages. Have you ever seen any construction company building them? Even in the first photo that is under construction, there is not any human worker in sight