[calm music] - [Narrator] This 28-mile stretch of I-40 in Western North Carolina is not your average highway.

For one, it bisects two massive wildlife preserves, the Great Smoky National Park and the Pisgah National Forest.

It's also an incredibly deadly corridor for wildlife, especially for black bears, white-tailed deer, and elk.

And lastly, this stretch of highway is busy.

Over the last 16 years, traffic on the road here has increased by 42%.

- It's such a small space for everybody to be on.

You know, you've got the mountain on one side, and you've got the river on the other side practically the whole way.

- Wildlife is getting hit and killed on the roadway.

That's a problem, right?

And then there's the public safety.

You don't want to run into an animal, much less a bull elk which can run 1,000 pounds.

- [Narrator] I-40 cuts through the hunting and mating grounds of these charismatic species, but there's also a longer term problem.

Warming temperatures due to climate change.

[calm music] - And in order to track climate, they're gonna need to go up the Appalachian chain.

That means crossing Interstate 40.

So the fact of the matter is, when we get to 35,000 vehicles or 40,000 vehicles or 45,000 vehicles a day, at some point in time, that corridor's gonna be an absolutely hard barrier, and practically nothing will be able to cross.

And that's a bigger problem than actually seeing dead bears on the side of the road, because wildlife needs to move.

- We wanna create safe passage from the biodiverse animals and wildlife in Great Smoky Mountain National Park to these areas in the northeast or other protected lands.

We wanna be able to mitigate and allow our wildlife to move so that they can, you know, survive some of these fluctuations that we're seeing in the environment.

- [Narrator] Thankfully, the needs of wildlife in this region align with the needs of the Departments of Transportation in North Carolina and Tennessee.

Five bridges along this stretch of highway need to be replaced starting with the Harmon Den bridge.

As DOT replaces these bridges, they'll be adding in features to make it easier for wildlife to cross the busy highway.

Here at Harmon Den, that means building two paths along the creek with nine-foot guardrails that guide animals there instead of over the highway.

- I mean, it's a whole culture shift of looking at all the users of the road and not just the cars or the trucks, but you have to look at all the users.

- [Narrator] Nationally roads kill about 12% of North America's wild mammals.

- A lot of the wildlife vehicle collision information we get, it's a small fraction, right?

And just kind of what you see anecdotally or what somebody reported.

- [Narrator] The 2021 infrastructure bill includes $350 million for wildlife crossings like this one.

The gold standard is, of course, a dedicated wildlife overpass like this one at Banff National Park in Canada or this crab crossing on Christmas Tree Island in Australia.

But these bridges are expensive.

- We essentially through this 28 mile section of road, want multiple, a linkage system, multiple opportunities for wildlife to cross through there.

So retrofitting what we already have, not to mention the structures that are already working but trying to get a dedicated wildlife overpass or two, those are the expensive things that can be the big elephant in the room, but truly I think to improve connectivity in the gorge and what we're talking about here, you know, in this large landscape, making sure important diverse wildlife can move, we need dedicated overpass or underpass structures for wildlife specifically.

- [Jeff] We need to actually accommodate these animals and their need to move.

And in the process we make it safer for the motoring public.