Elk, a Three-Sided Bridge, and Humans: Utah’s Perfect Precast Solution

Oct. 10, 2023
The Utah Department of Transportation (UDOT) faced a challenge: how to design and build a remote bridge structure that would provide safe passage for humans … and native elk species. Ultimately, a three-sided bridge offered the perfect precast solution.

Roads and other urban developments often bisect wildlife habitats, creating a need to provide connectivity between habitats to ensure greater protection and survival for an entire ecosystem. Elk migration patterns throughout a remote area of Utah required for a structure that was large enough to not disrupt their routine and strong enough to withstand traditional highway traffic.


When searching for an economical, environmentally friendly solution, the Utah Department of Transportation (UDOT) faced multiple challenges: the creation of an ecological solution to provide both road travelers and wildlife a way to coexist, and drive-time restrictions – due to the project’s remote location – that allowed for only a certain number of bridge sections to be delivered each day. Additionally, load rating the proposed three-sided bridge proved challenging, as the required rating software and methods had not been used on a three-sided “clamshell” bridge.

The Oldcastle Infrastructure team was integral in modeling the bridge in finite analysis software to calculate and incorporate the load rating into UDOT’s system. This project laid the foundation for the load-rating of three-sided bridges and developed processes to streamline future projects utilizing this product. 


Oldcastle Infrastructure provided the precast products for a three-sided bridge that offered the perfect solution for UDOT to create a large, open underpass crossing in a remote part of the state to allow elk to continue migrating safely past US-191.

To create the “clamshell” of the bridge, Oldcastle Infrastructure delivered 14 26’x8’ three-sided bridge units that, when combined, created a 26’x16’ unit measuring 54 feet in length.

Installation was detail-oriented and precise: first, a diversion around the highway was constructed to allow traffic to continue to travel; following this, the contractor began excavation. Despite logistical limitations due to drive-time restrictions and travel distance, installation of the three-sided bridge took just two days. The bottom seven units were set in one day, with the top units completed the following day.

Finally, the highway was reconstructed after the bridge was installed. The result? A good-looking, innovative, ecological solution that met the needs of UDOT, and the elk.


A three-sided bridge was the perfect product to design a system for such a project. It met the customer’s need for a highly constructible, precast solution, and satisfied the innovative planning, design, materials, and construction requirement within Accelerated Bridge Construction (ABC).

Why precast? There are many advantages and ways that choosing precast can enhance a project. Among them: Improved site constructability; expedited total product delivery time; enhanced work-zone safety for the traveling public; reduced traffic impact; shorter onsite construction time; and less weather-related time delays.