THis whole debacle is reminiscent of the boondoggle over caribou and moose crossings on the Trans Alaska Pipeline.
After batteries of experts claiming that the crossings 'had' to be different, because one would not cross under the pipeline and the other would not cross over where it was buried, millions of dollars were added to the cost of the pipeline, and it turned out either critter would just cross where it could.
It makes me wonder if some of the same idiots were pulling the strings on this.
I have seen this in a couple places... Kinda by Snoqualmie Pass IIRC. and another up by Banff... I would be interested to see if traffic accidents went down after their installation. They have been there long enough to show a difference.
And that is the difference, btw, wrt your example. In this case, if you can keep the wildlife off the highway, it would pay for itself in untold accidents, the cost in lives, the costs in cleanup...
But it is also a choke point that predators would learn to use, which might tend to hinder crossings.
So I dunno. I'd have to see the numbers to prove it, I guess
