Looking west across the Pretty Rocks slide area in September 2021/NPS

Work to build a way around the Pretty Rocks landslide in Denali National Park in Alaska is set to begin this summer and operate on an accelerated schedule to complete the task by 2024.

Last October park officials said the slides that have occurred in the area between milepost 44 and milepost 46 since the 1990s will require that about half of the 92-mile road will remain closed for the 2022 visitor season. During the 1990s, the Pretty Rocks landslide caused small cracks in the road surface, but they increased to three-and-a-half inches per day by 2020. Of some 150 unstable sites on the Park Road, Pretty Rocks is the “problem child,” relentlessly encroaching even after it’s shored up, park geologist Denny Capps told the Traveler's Rita Beamish in 2019.

Twenty-five-million-dollars for the project was announced in January, with the funding coming from the Bipartisan Infrastructure Law.

During construction, visitors will continue to have access to wildlife viewing, views of Denali, front-country trails and backcountry hiking and camping, the Park Service said Thursday evening in a release. 

“Denali is ready for visitors in 2022 and will continue to work with our neighbors, inholders and partners to ensure an unforgettable Denali experience for visitors throughout the construction phase,” said acting Denali Superintendent Brooke Merrell.

The Park Road will remain open to mile 43 until completion of a 400-foot-long bridge spanning the slide area. The first phase of the project will restore road access to areas west of the project area by constructing a steel bridge to span a slow-moving rock glacier that has accelerated in recent years beyond the capacity of the park to maintain a safe road surface, resulting in a road closure in August 2021. The project will also address several other geologic hazards that threaten public safety and infrastructure along the 92-mile Park Road.

In addition to the construction of a bridge, the Polychrome Area Improvements project would also include the following actions:

• Excavation of uphill slopes
• Placement of excavated material on the slope below the road
• Slight road realignment and temporary widening of the road
• Construction of retaining walls and drainage improvements
• Creation of rockfall ditches and benches
• Rock scaling and/or installation of rock bolts and dowels
• Construction of a temporary platform for bridge assembly
• Construction of a partially buried retaining wall along approximately 1,000 feet of road