# Granite Navigates Denali's Moving Ground - **Published:** 2026-11-10 - **Edition:** West - **Source:** Construction Equipment Guide - **Authors:** Larry Bernstein – CEG CORRESPONDENT - **URL:** https://www.constructionequipmentguide.com/granite-navigates-denalis-moving-ground/72754 - **Tags:** Alaska, Bridges, Granite Construction, National Parks ## Summary Granite Construction achieved substantial completion of a project on the Polychrome Pass Bridge that will allow visitors to continue enjoying the entire length of Alaska's Denali National Park and Wildlife Preserve. ## Article The Golden Gate Bridge, the Tower Bridge and the Brooklyn Bridge are three of the world's most famous bridges. Far fewer people are familiar with the new Polychrome Pass Bridge, yet it's a grand, impressive structure. In summer 2026, Granite Construction achieved substantial completion of a project on the Polychrome Pass Bridge that will allow visitors to continue enjoying the entire length of Alaska's Denali National Park and Wildlife Preserve. ## Growing Problem, Significant Solution The project genesis was the Pretty Rocks landslide. According to the National Park Service, “Pretty Rocks landslide has been active since at least the 1960s, and probably since well before the Denali Park Road was built … in 1930.” The landslide, around mile 45.4 of Denali National Park Road, affects road access to the western portion of the park. The long-occurring landslides were a minor issue for years, as they were only moving inches per year. The National Park Service said, “The landslide only caused small cracks in the road surface and required moderate maintenance every 2–3 years.” However, by the summer of 2021, the movement had increased to more than a foot per day, making continued maintenance and safe passage impractical. The National Park Service was forced to close the road, leaving nearly 47 m. of the road inaccessible and cutting off access to the western portion of the park. Hence the need for the Polychrome Pass Bridge, which will provide a permanent crossing over the active slide rather than repeatedly rebuilding a road on unstable ground. Granite Construction Project Manager Patrick Murphy told Construction Equipment Guide that the work will also address several related geologic hazards. “In addition to spanning the Pretty Rocks Landslide, the project includes slope stabilization, permafrost protection, drainage work, excavation, road realignment and improvements near the adjacent Perlite Landslide,” he said. ## Collaboration Determines Ideal Bridge Type The Polychrome Pass Bridge itself is fairly conventional. It's a 475-ft.-long, 50-ft.-tall, and 26-ft.-wide, single-span steel truss bridge. The width between the guardrails is 19 ft. While the width supports two lanes, the approach and departure angles make two-way traffic on the bridge tight. Other work on the project includes: • approximately 70,000 cubic yards of controlled blasting, selective excavation, and rock bolting to leave a natural-looking rock face; • road realignment at the bridge approaches, including geometry needed to accommodate buses; • micropiles, ground anchors, rock bolts or dowels, to anchor the abutments; • precast, post-tensioned, grouted concrete abutments; • a soil-nail wall and other slope-stabilization measures to protect the abutments; • thermosyphons to maintain permafrost ice layers beneath and around the east abutment; • drainage improvements; • retaining wall construction near the Perlite Landslide; and • bridge approaches, deck coating, final grading and site restoration for demobilization. Selecting the bridge type and building the bridge itself, however, were far from ordinary. Originally, the team was contemplating constructing an Acrow-type pre-engineered modular bridge,” Murphy said. “During the pursuit, we determined that the proposed modular bridge concept could not span the required distance and that the original budget and schedule were not sufficient for the conditions.” The Granite team recommended a collaborative delivery model because the geotechnical challenges required participation from all parties, including the Federal Highway Administration, the design firm and the contractor, to resolve, Murphy said. Originally, the project was going to be delivered via design-build, but the owners shifted to CMGC. The shift to CM/GC delivery was particularly important because it allowed Granite and its specialty partners to participate with the FHWA's designer, Jacobs, before the design was complete. “We were able to review constructability, developed the launch method, investigated temporary-foundation needs, packaged work for early procurement, allocated risks and negotiated each major package as the design matured,” Murphy said. “This preserved the existing designer's and geotechnical consultant's knowledge while adding construction and erection expertise early enough to influence the solution.” Ultimately, the team determined that a truss bridge was ideal. “Geological conditions did not support a two-sided cantilever, so the team pivoted to a single-sided launch from a semi-balanced cantilever state with a smaller launch nose truss initially spanning the gap,” Murphy said. ## Challenging Conditions Impact Bridge Erection Large general contractors like Granite deal with challenging conditions all the time. However, the situation in Denali was unique because conditions were changing as the project progressed. The landslide remains active. In addition, conditions vary substantially across the site. “Conditions on the site range from competent basalt to loose colluvium and ice-rich permafrost and these materials surround an actively moving landslide,” Granite Vice President Todd Keller told Construction Equipment Guide. “The geology encountered in one location could differ significantly from conditions only a short distance away.” Getting materials to the job site, which has limited staging space, was also challenging. Many materials were handled multiple times before being incorporated into the project. Keller described the journey of steel bridge components. A Midwestern mill produced the steel components, freighted to the fabricator in Portland, hauled to a shipping port in Seattle, barged north to Whittier, Alaska, freighted by rail to Fairbanks, loaded on trucks for delivery to an offsite yard near Denali Park, and then broken into loads suitable for transport into the park on “clean” trucks. All loads delivered inside the park need to be cleaned and inspected for invasive species. Loads for delivery to laydown yards within the park generally had to move at night to avoid conflicts with visitor bus traffic. The lack of space in the area also impacted the crew. There's no housing nearby, so the team established a self-contained worker camp approximately 18 mi. away. Food and water were brought in, and waste was removed regularly. Since the park is home to grizzly bears and other opportunistic wildlife, all food and refuse was stored in locked, bear-proof containers. Erecting the bridge also challenged the team. “We designed a unique launching system involving temporary foundations, launch frames, specialty rollers and jacks, and a temporary launching truss installed within the permanent truss,” Murphy said. The team incorporated the temporary truss within the permanent truss to enable the launch. Bridge erection required a specialty Liebherr 60-ton crawler crane that could fit within the permanent bridge truss and hoist all bridge members for piece-by-piece erection. To reduce fabrication and erection risk, the subcontractor completed a trial assembly at the fabricator's Portland facility. The team assembled the full bridge there over approximately two months, disassembled it, then shipped it to Alaska. ## Successful Project Project construction began in summer 2023 and was substantially completed in summer 2026, although cleanup work remains. Construction finished ahead of schedule and under budget with a total project cost of just under $208 million. This is especially noteworthy given the challenges noted above and the particularly short construction seasons. ## Photos ![Cat equipment moves dirt on the mountainside on the Polychrome Pass Bridge project.](https://dmt55mxnkgbz2.cloudfront.net/1205x0_s3-72754-W-188_26-LB-1_JPG-b478c759e150b452e5ae714c63b9c93d.jpg) *Photo credit: Granite Construction photo* ![In the early days of the project, it was possible to maintain a road across the landslide.](https://dmt55mxnkgbz2.cloudfront.net/1205x0_s3-72754-W-188_26-LB-2-443bc09def59832f043e72364f284bb4.jpg) *Photo credit: Granite Construction photo* ![The truss bridge](https://dmt55mxnkgbz2.cloudfront.net/1205x0_s3-72754-W-188_26-LB-3-574ee29d335c05d661545c655aea4b8e.jpg) *Photo credit: Granite Construction photo* ![The launch truss was secured on the far side.](https://dmt55mxnkgbz2.cloudfront.net/1205x0_s3-72754-W-188_26-LB-4-a69960f1f423d37b1f7b18e9e1283516.jpg) *Photo credit: Granite Construction photo* ![The launch truss was completely assembled inside the structure of the main truss.](https://dmt55mxnkgbz2.cloudfront.net/1205x0_s3-72754-W-188_26-LB-6-ad1ba4c276197570c7b3e7794bf6026c.jpg) *Photo credit: Granite Construction photo*