Safe Passage

The I-40 Pigeon River Gorge Wildlife Crossing Project

great smoky mountains national park

Why focus on the Pigeon River Gorge?

Aerial photos of I-40 in the Pigeon River Gorge by SouthWings.

By Steve Goodman, Safe Passage Co-Research Lead and Conservation Biologist for National Parks Conservation Association

Safe Passage is on a mission to improve wildlife’s ability to safely cross I-40 in the Pigeon River Gorge, resulting in improved public safety.

But, from a large landscape perspective, why have we chosen to expend valuable conservation and transportation resources here? And why now?

First, looking at a map of protected lands across the U.S., there is much less protected land in the East, and Great Smoky Mountains National Park and the surrounding national forest lands make up a substantial portion of it (Figure 1).

Furthermore, we’re right in the heart of The Nature Conservancy’s resilient and connected network designed to sustain biodiversity under a changing climate (Figure 2). This habitat corridor is critical for the long-term flow of regional plants and animals, yet I-40 has become a major barrier to wildlife movement. Researchers have estimated that in the Eastern U.S., only 2% of natural land areas retain enough connectivity to adequately allow plants and animals to track climate change. By adding wildlife corridors, we have an opportunity to increase that percentage tenfold.

Most compelling in a visual sense, however, is the now-famous Migrations in Motion map (Figure 3), produced by The Nature Conservancy. Based on modeling of the climactic needs of individual species, this animated map illustrates predicted movement routes of around 3,000 mammal, bird and amphibian taxa under current climate change projections, many of which are expected to track through the spine of the Southern Appalachians, including the Pigeon River Gorge.

Figure 1 – (Click to enlarge)
Figure 2 – (Click to enlarge)
Figure 3 – (Click to visit animated map)

Spring signals a time for elk movement in the mountains

Elk 30216 and her calves throughout the years. During Safe Passage’s road ecology research in the Pigeon River Gorge, GPS collars revealed multiple years of one mother elk’s journey to and from her calving area.

While the elk population in and around Great Smoky Mountains National Park does not migrate, they do make some relatively longer seasonal movements. In these spring months, pregnant females will move away from their herd to give birth in isolated areas. Cows usually carry one calf and give birth in late May through June. In late summer when the calf is large enough, the pair will rejoin their herd, just in time for the rut (mating season) that occurs in late September through early October.

During our road ecology research in the Pigeon River Gorge, elk monitoring with GPS collars revealed multiple years of one elk’s journey to access her calving area. In both years of monitoring, she left the Cataloochee Valley in early spring and crossed the interstate to access her calving area north of the roadway.

In late summer, the cow and her calf would begin their journey back to the park, again having to navigate crossing I-40. In the two years of monitoring, this elk crossed I-40 107 times, with the majority of those crossings occurring at the Tennessee–North Carolina state border, where the Appalachian Trail crosses under the interstate via a road bridge, and also across a road surface just north of that area. 

In the map to the right, you can see her many crossings throughout the years — which she made both with and without her calves in tow, depending on the time of year. Each dot on the map represents the hourly location of this particular elk, Elk 30216.

— Liz Hillard, Safe Passage Co-Research Lead

Safe Passage research revealed the annual journey of one female elk, including 107 trips across I-40. Click the image to enlarge.

Science Blog: Not just about the bears – Researchers consider mesocarnivore needs in Safe Passage study

By Steve Goodman, Volgenau Wildlife Research Fellow with National Parks Conservation Association & Co-research Lead for the Pigeon River Gorge Wildlife Connectivity Study

Though the target species of our Safe Passage research are black bear, elk and white-tailed deer — selected because they are relatively easy to monitor and are of the highest concern from a driver safety perspective — they’re not the only animals we’ve studied through this project.

We’ve also collected data on mesocarnivores, which are small to mid-sized mammals whose diets are mostly comprised of other animals, and we are assessing their needs for safe passage under Interstate 40 as well. Mesocarnivores in our study area include bobcats, coyotes, gray foxes, long-tailed weasels, otters, raccoons, red foxes and Eastern spotted skunks.

While improving safe passage for larger mammals should, in general, benefit smaller critters too, several mesocarnivores have very specific requirements that we also must consider when planning new structures or improving existing ones.

We also always work on increasing our understanding of the needs of even smaller animals — like frogs, salamanders and snakes — but that is for a future blog.

Through wildlife camera research in the Pigeon River Gorge, Safe Passage researchers have observed these mesocarnivore species (and more), just within the forested I-40 right-of-way.

NCDOT to begin construction on wildlife crossing at Harmon Den

The bridge over Harmon Den Road at Interstate 40 Exit 7. Photo courtesy of Google Maps Satellite imagery

On Nov. 3, 2021, the North Carolina Department of Transportation announced preparations for significant construction on Interstate 40 over Harmon Den Road, at Exit 7 in Haywood County. Starting as soon as Nov. 9, a contractor for the NCDOT will begin work to replace the bridge at this exit, integrating wildlife crossings into the new structure.

The Harmon Den area has long been a hotspot for wildlife-vehicle collisions, and Safe Passage: The I-40 Pigeon River Gorge Wildlife Crossing Project has advocated for building a wildlife crossing at this location. When the NCDOT announced plans to replace the existing bridge structure here, Safe Passage and its partners collaborated with the agency for a safe solution to fit this particular site.

The plans for the new Harmon Den bridge include two paths — one on each side of Cold Springs Creek — to help wildlife migrate from one side of the interstate to the other without encountering vehicles. A 9-foot tall fence will guide animals to the trails, away from traffic and under the bridge. 

NCDOT is also evaluating the use of wildlife guards — similar to slotted cattle guards — to prevent deer and elk from walking up the ramps. These measures will hopefully encourage wildlife to cross under the bridge and reduce the possibility of animal accidents. 

“We are excited to be adding protections for wildlife in this and other upcoming NCDOT projects,” said Division 14 Engineer Wanda Austin in a press release from the NCDOT. “We have worked with a wide variety of interest groups, transportation, and wildlife experts to incorporate these unique features to benefit the people who drive the gorge, and the animals that live in the gorge.”

Austin has been a participating stakeholder in the Safe Passage collaborative since its inception in 2017.

The traffic management plan for this project includes a six-month detour around the bridge, with drivers utilizing the exit and onramps. 

In late October and early November, construction crews from contractor Kiewit Infrastructure South have been mobilizing equipment and preparing to begin significant construction activities. By the first week of November, crews had already begun upgrading the exit and entrance ramps. 

As soon as mid-November, all traffic will be funneled into a one-lane pattern prior to the bridge and will use the ramps as a detour around the bridge. Traffic will remain in this pattern into May 2022 while crews remove and replace the deteriorating structure. 

In a feature article published by the Asheville Citizen Times on Nov. 5, Jeff Hunter, National Parks Conservation Association senior program manager and Safe Passage facilitator, thanks the NCDOT for its collaborative work to make I-40 a safer place for wildlife and motorists alike.

Black bears, elk, whitetail deer and other, smaller animals live in the surrounding mountains and naturally migrate across the area — and across the highway — looking for food, mates and habitat, Hunter told the Citizen Times.

In addition to the unique wildlife features, this five-bridge project is also the first of its kind in the state to be administered in a new method with the intent of forming a partnership between the NCDOT, the contractor and the design team. Kiewit Infrastructure earned the $19 million contract for the first of the five, which has a final completion date set in May 2024.

Exit 7 from I-40, where construction will soon begin to replace the existing bridge structure and add crossings for wildlife.

The current I-40 overpass as viewed from Harmon Den Road.

The result of the new construction manager/general contractor method is lower costs and expedited delivery from the first step in the design phase to the last inspection of the new bridge, and new safe passage underneath.

Drivers desiring to go from Asheville to Dandridge, Tenn., may choose to take I-26 West to Kingsport and then I-81 South to Dandridge. This route adds about 45 minutes to driving time compared to a typical trip through the gorge.

Accommodation or decimation: It’s time to choose how we share our mountains

Before you can solve a problem, you have to understand it. Like many other roadways around the nation, the Safe Passage project area — a 28-mile stretch along I-40 in western North Carolina and east Tennessee — has created a “barrier effect” for wildlife, fragmenting species’ habitats and separating wild animals from their needs.

Safe Passage is part of a growing national and global effort to create safe crossings for wildlife. Using a study and process known as road ecology, Safe Passage aims to help its target region plan and implement a variety of crossing structures, from culverts to bridge extensions and overpasses, designed just for animals.

A combination of fencing and crossing structures has been used successfully in countries all over the world, from France and Germany to Singapore and South Korea. In North America, Canada and Mexico have also successfully created effective crossings, and now, states like California, Colorado, Texas, Virginia, Washington and Utah are focusing on road ecology too.

Before coalition partners can begin increasing highway safety for animals and humans alike, states’ Departments of Transportation need scientific data to make informed plans. For the last two years, National Parks Conservation Association and Wildlands Network have been conducting field research to evaluate how roadways outside Great Smoky Mountains National Park influence black bear, white-tailed deer, and elk.

The researchers’ multi-faceted approach assesses wildlife’s use of existing structures, road mortality, and activity within the highway right-of-way. It also identifies and predicts elk road-crossing locations using movement information from GPS-collared elk. This will help identify areas along the interstate where mitigation strategies such as fencing and crossing structures could be best implemented to reduce wildlife–vehicle collisions and increase habitat connectivity.

Safe Passage shares Wildlife Crossings in the Smokies virtual program video

On January 28, Safe Passage hosted an educational virtual program with Jeff Hunter, senior program manager with National Parks Conservation Association in Asheville. In a free online event, facilitated through Zoom, Hunter spoke on recent innovations to provide safe passage options for wildlife. The event was co-sponsored by the Tennessee Citizens for Wilderness Planning and the UT Arboretum Society.

Hunter’s work includes issues related to Great Smoky Mountains National Park, the Blue Ridge Parkway, and the Appalachian National Scenic Trail. He also led the Tennessee Wild wilderness campaign focused on permanently protecting nearly 20,000 acres in the Cherokee National Forest, including 4.5 miles of the Appalachian Trail.

To host your own presentation (currently virtual-only, but with in-person availability in the future) for your civic group, organization, school or classroom, please visit our Educate Your Group page and inquire about event bookings.