Name: Wildlife crossings stop roadkill. Why aren't there more?
Uploaded: 2023-07-08T21:01:20.000Z
Duration: 6 min 37 s
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When you're driving down the highway, it's hard to avoid a deer

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By the time you do see it, it's often too late.

But what if there were crossings for animals, just like the ones used by humans?

In some places, planners have built exactly that.

And data shows that animals are using them,

which means that close calls like this are far less likely to happen.

Hitting an animal is a risk anywhere roads are built through animal habitats.

And as more roads are built, there are more opportunities for collisions.

According to a 2008 study commissioned by the US Congress, the number of animal-vehicle collisions was increasing.

Experts blamed the rise on more vehicle miles traveled combined with a growing North American deer population.

But the official tally excludes accidents that have less than $1,000 in property damage.

If you account for minor collisions, unreported accidents, and other variables,

experts estimate at least one million collisions with large animals—meaning deer, elk, and moose—occur every year in the United States.

And while animal-vehicle collisions rarely cost lives, they do cost money.

In the US, wildlife-vehicle collisions cost over 8 billion dollars every year—

money that is spent on vehicle repairs, medical costs, and other expenses.

And although humans tend to survive, animals often get killed.

In the same report, researchers found that vehicular traffic threatened 21 endangered species, including the bighorn sheep.

In some places, highway planners have solved the problem by building fences to keep animals off the road.

A relatively cheap solution that has been proven to reduce roadkill by over 50%.

But although fencing reduces roadkill, it neglects a wider problem.

Besides the risk of collision, roads harm animals by dividing wildlife populations and limiting their ability to find mates, food, and other necessities of life.

In Canada, wildlife scientist Tony Clevenger has been studying how road construction affects animals in Banff National Park.

It can have important impacts on the reproductive success

because females aren't being able to access important spring habitat,

because they are not crossing the highway.

So, it's important that we maintain these movements and we maintain this access to the important biological resources throughout the year.

And wildlife crossing structures do that.

Beginning in the 1980s, authorities began installing a system of underpasses and overpasses in Banff.

The structures were designed for animal use only and were located where animals were likely to cross the road.

The data speaks for itself, for example, here on the Trans-Canada Highway in Banff National Park,

there were, on average, more than a hundred elk-vehicle collisions per year before the fencing and the wildlife crossing structures,

and now it's down to less than a half-dozen.

So these are huge reductions, by having these mitigation measures in place that are improving motorist safety; they're saving lives."

And also, in a protected area like Banff National Park, it's important because the objective of this National Park is to protect wildlife.

Instead of blocking the road entirely, planners used fences to funnel wildlife towards the crossing structures, which were planted with native vegetation.

A few species, like deer, elk, and moose, immediately started using them.

And were followed by more skeptical species, like wolves and grizzlies.

Within a few decades, even the most reluctant species, like lynx, had adapted to using the crossings.

In 2012, a male grizzly was recorded crossing the structures 66 times in one summer.

By crossing the highway, the bear's habitat expanded to include potential mates on the other side of the road,

which decreases the likelihood of inbreeding.

What we've been able to show is that by having these overpasses and underpasses in place,

we've restored genetic connectivity across the highway here in Banff National Park.

Wildlife crossing structures are fairly common in some parts of the world, particularly in Western European countries like the Netherlands.

But there are relatively few in North America.

And the success of the Banff crossings has encouraged similar projects in the United States, like this rendering of an overpass being built in Washington State.

And in 2012, the Wyoming Department of Transportation built an overpass that reconnected an ancient migration route of the pronghorn antelope.

So, if these crossings are improving safety and restoring habitats, why aren't they everywhere?

Probably the biggest factor that would limit construction of wildlife crossings is cost

and having the funding within the transportation agency budgets to build these wildlife crossing structures.

Structures can save money in the long run, but the initial investment is significant.

Constructing an overpass like this one in Banff typically costs several millions of dollars.

So to create more cost-effective solutions,

Clevenger organized a design competition with a group of experts that included ecologist Nina-Marie Lister.

They named it ARC, short for "animal road crossing".

Our argument was, for the money that was spent, you could be getting a lot more value,

if you designed them specifically for the target client, which is wildlife and humans driving underneath them.

Instead of adapting traditional plans from highway engineers,

ARC encouraged different stakeholders to collaborate on structure design.

There had to be a landscape architect, an architect, and an engineer, as well as ecologist.

you had a very different way of designing a structure and we asked for them to be ecologically sustainable.

They also had to consider materials that were recyclable, reusable, modular, and moveable.

The contest was a success and ARC generated groundbreaking solutions,

including a winning design that reduced costs and improved safety by removing the need for pillars on the highway.

The cost of that overpass was about 30 to 35% cheaper than overpasses that were being built at the same time in Banff National Park.

The state of Colorado agreed to build the design, but more immediate needs, including a flooding event in 2013, have prevented development.

The design was never built, but that doesn't mean it won't be.

As climate change strains ecosystems and reduces habitats,

animals will change their patterns of movement and the need for effective crossings will become even more acute.

To solve the problem, Lister hopes that planners will return to the ARC designs, which remain viable solutions.

These things work and they solve the problem once and for all.

So, if you build a network of these bridges that connect in the right places, you've solved the problem for good.