by Yereth Rosen, Alaska Beacon
June 3, 2023

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 three 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, as it did on the first Friday in May, 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 May 5 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.

Dave Schirokauer, Denali National Park’s science and resources team leader, stands on May 5 at the East Fork turnaround site on the park’s road, at about mile 43 of the 92-mile route. Tour buses can go no further on the road because of the closure a couple of miles to the west at the dangerous Pretty Rocks landslide site.

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. A recent discovery that 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.

 Tourist businesses lining the Parks Highway outside of the Denali National Park entrance, at a strip nicknamed “Glitter Gulch,” are seen on May 5. The shops, restaurants and tour companies, not yet open that day, depend on Denali crowds. Last year, with the second half of the road closed, there were more opportunities for some companies but challenges for others, like restaurants, which did not have the staffing to manage crowds.

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.

Last year, 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.

This year, with Alaska on track for a record 1.6 million cruise passengers, the crowds are expected to be bigger. But Denali should be able to handle the increased traffic, even with half the road closed, said Brooke Merrell, the park’s superintendent.

“We feel like we got a good practice year last year to make sure we have it right,” she said. “We believe we’ll be able to accommodate it with the part of the road we have this year.”

 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.

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.

How the construction affects Alaska tourism

The tourism industry has been adjusting to the new reality.

For local companies, last year was a “mixed bag,” with some operators able to take advantage of increased traffic resulting from the shorter bus trips but others struggling, said Vanessa Jusczak of the Denali Chamber of Commerce, based in Healy. Excursion companies had more business, but short-staffed restaurants were burdened by crowds appearing at what were normally low-volume times, she said by email.

In Anchorage this summer, Denali-bound tourists appear to be well aware of the road closure, said Jack Bonney, vice president of the Anchorage Convention and Visitors Bureau.

“It doesn’t seem to be affecting their choice about whether they go to Denali or not,” he said. While “the closure is in the back of people’s minds,” the park continues to be seen as an attractive destination, he said.

More than people are affected by the road closure. The park service is embarking on a study of bears to see how the lack of road traffic might be affecting them, Schirokauer said. The plan is to collar 18 to 20 animals, with half on the east of Pretty Rocks and the other half on the west side where the road is closed, he said.

Landslides increasing across the north

While Pretty Rocks is a dramatic and visible case because of its location and the inconvenience it is causing, thaw-induced landslides are increasing all over the north.

Within the Denali road corridor, more than 140 landslide-prone sites have been identified.

Along other roads in Alaska, there are dangers in other national parks and sites outside of parks. Those include Slate Creek along the Parks Highway just outside Denali’s entrance, where permafrost thaw appears to be combining with extreme rainfall to create potential maintenance headaches and threats to a recently installed fiber-optic cable and other infrastructure, and the Dalton Highway, the sole land route to the North Slope oil fields, where thawing “frozen debris lobes” of ice, dirt, rock and vegetation are creeping downslope and forcing diversions and adjustments. East of Alaska, in Canada’s Northwest Territories, thaw-triggered landslides and slumps are eating away at the Dempster Highway.

Away from roads, big hazards come from thawing mountainsides, especially of coastal mountains, where dumped debris can cause localized tsunamis. One landslide hotspot is northern Southeast Alaska, where tall peaks rise dramatically from glacial fjords. There, and in neighboring parts of Canada; the pace of landslides is accelerated through  combined glacial retreat and mountain permafrost thaw that destabilizes slopes. In 2015 in Taan Fjord, a coastal area of Wrangell-St. Elias National Park, the side of a mountain collapsed, sending rocks and debris into the water and triggering a local tsunami that reached over 630 feet, making it the fourth highest ever recorded. No people were affected by that, but the story was different in Greenland in 2017, when a massive landslide in a glaciated area caused a tsunami that killed four people.

In Denali, the Pretty Rocks bridge will not be the end of the work. The federal funding secured for the bridge is also intended to cover a second project phase to address another unstable site less than a mile to the east called Bear Cave.


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