Safe Passage

The I-40 Pigeon River Gorge Wildlife Crossing Project

Harmon Den

Habituation at Harmon Den: Next steps for wildlife after crossing construction

After crossings are constructed, how soon can you expect wildlife to adapt to use new, safer passages?

Though infrastructure has been installed at the Harmon Den bridge in North Carolina (pictured above), more still must be done to attract wildlife to use the safer crossing. 

Progress is being made at the Harmon Den bridge in North Carolina, where our partners at the N.C. Department of Transportation recently constructed infrastructure for wildlife. Since then, we’ve begun some early monitoring of how wildlife are interacting with the new crossings, which include wildlife-friendly benches and cattle guards and will, in the future, include fencing.

Of course, it may take some time for wildlife to habituate to this improved crossing opportunity in the landscape, especially while vegetation in the area is still recovering from the recent construction. To improve success, it’s important that creekside vegetation — like fast-growing tulip popular, black birch, and red maple — continues to reestablish, as it will provide important cover and protection for traveling wildlife. Consideration should also be given, however, to restricting tractor trailer parking along the on- and off-ramps, which — because engines are often left running — creates noise and garbage (including human waste) that may potentially deter wildlife movement toward the new crossings. Another opportunity to encourage wildlife to use the crossings would be to clean up the crushed concrete spill that occurred during bridge construction along the bank of Cold Springs Creek.

Finally, it is important to note that although the opportunistic wildlife improvements at Harmon Den are important for wildlife connectivity and reducing vehicle collisions long-term, there are limitations to combined human–wildlife structures when compared to standalone structures for wildlife only. The Safe Passage Fund Coalition has made several research-based recommendations for standalone wildlife structures north and south of Harmon Den.

— Steve Goodman, Safe Passage Co-Research Lead

Day versus night view from the wildlife crossing at Harmon Den. Trucks parking on the on- and off-ramps can discourage wildlife from making the safe trip under the highway.

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.