Source: Yereth Rosen, Alaska Beacon

By midsummer in 2026, visitors will likely be traveling over a sophisticated new bridge that clears a geologic hazard that has become a poster child of climate change in Alaska.

Until then, the National Park Service and the tourism industry will be coping with two more years of shutdowns at about the halfway point of the sole park road to avoid ongoing landslides at a steep and perilous site called Pretty Rocks.

Where there used to be a curve at about mile 45 of the 92-mile road, a site known for its spectacular views of a valley called the Plains of Murie, a section of road is now gone, leaving a nearly sheer drop-off in its place. When the sun hits the rock face on the north side, clumps of dirt and rock tumble almost incessantly down the slope.

In August of 2021, the road was closed there; that section was still intact but deemed too dangerous for public travel. By then, the perils were obvious, said Dave Schirokauer, Denali’s science and resources team leader. He pointed to a site on the now-collapsed road section. “Right over there in the corner, we could see ice. Very, very ice-rich permafrost was at the surface and was very visible,” he said during a 2023 tour.

Pretty Rocks got this way in Hemingway-like fashion: gradually, and then suddenly.

The slope was moving slightly in the 1960s and likely for decades earlier, according to the park service. But prior to 2014, it was causing little trouble beyond some occasional small cracks in the road surface, according to park officials. As the climate continued to warm, slope movement that was measured in inches per year before 2014 increased to inches per month in 2017, inches per week the following year, inches per day in 2019 and, in 2021, 0.65 inches per hour, according to park officials. A collapse in August of 2021 forced the abrupt road closure and an early end to some Denali trips.

The project to reopen the road at Pretty Rocks, expected to cost about $100 million, is challenging. The site is remote and steep. The bridge has to be suitable for permafrost terrain, strong and secure enough to carry tour buses and withstand earthquakes, subtle enough in appearance to blend in with surroundings and constructed in a way that minimizes impacts to park visitors and wildlife.

The design includes anchors to lodge vertically and at angles. It also includes 23 thermosyphons – devices that pull heat out of the ground — to preserve a pocket of ice-rich permafrost discovered 85 feet below the surface at the east end, said Steve Mandt, the park engineer coordinating the project.

Site geology pushes back road opening

The site’s geology makes any fix complex. There is permafrost overlain with a rock glacier, which is a frozen but thawing conglomeration of rock and ice. There is clay, which thaws at a lower temperature than that needed to melt ice. There is rainwater that infiltrates all that and, depending on the season, expands the ice or hastens the melt. “So you’ve got rock, you’ve got rain that freezes and you’ve got this major ice layer that’s moving,” Schirokauer said.

The clay has proved particularly problematic. Workers will have to remove 80,000 cubic yards of clay on the west side of the planned bridge site rather than the 30,000 previously estimated means a one-year delay in the project’s expected completion, said Denali spokesperson Sharon Stiteler.

The change from a 2025 road opening is a setback to the tourism industry.

“With the additional delay, obviously, that is disappointing,” said Jillian Simpson, president and chief executive officer of the Alaska Travel Industry Association. But the road is “a critical piece of infrastructure” and the industry understands “how important it is to get it right,” she said.

“Denali is the linchpin of tourism when it comes to exploring Alaska on land,” Simpson said.

As the bridge becomes reality, Denali will be busy with more than the usual tourist crowds.

A camp at the park’s gravel site operated over the next summer seasons will serve 50 or more workers who will shuttle back and forth, their vehicles in some places alternating with the tour buses.

The approach to the Pretty Rocks site is so narrow that work trucks are to be backed in because there is not enough space for large vehicles to turn around. There will be some noise, like from pile driving, though the plan is to keep that to a minimum.

For tourists, this will be another year of stopping at the site called East Fork at the road’s 43-mile point, where there is a temporary ranger station in a yurt and enough space for buses to turn around.

“This is the new Eielson,” Schirokauer said, referring to the temporarily closed Eielson Visitors Center at the road’s 66-mile point, normally a popular stopping and turnaround site.

In 2022, the first full year of the closure at Pretty Rocks, visitation bounded back from extreme lows resulting from the COVID-19 pandemic, though it was still only 88% of typical pre-2020 levels, according to an analysis by the Alaska Department of Labor and Workforce Development. Those who came to Denali were curious about the landslide, park staffers said. Many who rode the bus as far as they could, to the East Fork turnaround, walked the extra distance to see the site for themselves, Stiteler said.

A temporary staircase at the East Fork turnaround area on the Denali National Park road, seen here in May of 2022, gives visitors access to the river plain below the roadbed and a route for exploring park territory beyond the Pretty Rocks closure area. (Photo provided by National Park Service)

It remains possible to travel around Pretty Rocks to the western half of the park.

There is temporary access provided by a steep stairway from the East Fork bus terminus to the river valley below. About 15% of the visitors who rode the shuttle bus that far last year chose to make that descent for brief walks or even more extensive hikes, according to park staff. 

Backcountry users with the appropriate permits can keep going from there to explore the territory that is currently beyond park road access. Well-heeled travelers can, moreover, fly into Kantishna, the patch of private land at the end of the road, and stay at deluxe lodges where daily rates are well above $1,000.