Polychrome Pass Bridge Restores Access Across Denali’s Pretty Rocks Landslide

Polychrome Pass Bridge Restores Access Across Denali’s Pretty Rocks Landslide

After five years of planning, engineering, and construction, the Polychrome Pass Bridge is complete. The new bridge restores access across the active Pretty Rocks Landslide and reconnects the eastern and western portions of Denali Park Road for the first time since the 2021 closure. The project delivers a long-term solution that restores access to destinations beyond the landslide while preserving one of America's most treasured landscapes.

Built in one of North America's most remote and environmentally sensitive locations, the project required innovative engineering and close collaboration to address active landslide movement, seismic considerations and ice-rich permafrost. Through a collaborative CM/GC delivery approach, project partners worked together to identify risks early and develop solutions tailored to the site's unique challenges.

At the heart of the project is a 475-foot single-span steel truss bridge that safely carries traffic above the moving landslide. Supported by complex foundation and slope stabilization systems, the bridge was designed to perform in one of the nation's most dynamic geologic environments while minimizing impacts on the surrounding landscape and visitor experience.

One of the project’s most innovative features is the use of thermosiphon technology to protect the ice-rich permafrost beneath the bridge’s eastern abutment. The passive cooling system removes heat from the ground and helps keep deep permafrost frozen year-round. Backed by extensive geotechnical investigations, monitoring, and foundation design expertise, the bridge represents a significant advancement in cold-regions engineering.

With the completion of the Polychrome Pass Bridge, Granite, along with many project partners, has delivered a durable transportation solution that will help preserve access to Denali National Park for generations to come. To learn more, check out the Polychrome video series to get an inside look at the journey of bringing this project to life.