A slumping section of the Denali National Park road dropped an unprecedented amount over the winter, underscoring the need for a planned bridge over the unstable stretch of road near Polychrome Pass.
The Pretty Rocks landslide is the result of movement — accelerated by climate change — of what’s known as a rock glacier underlying the road.
Denali National Park acting superintendent Brooke Merrell says crews clearing snow from the road earlier this month found significant new slumping at the site.
“It was really sobering to arrive on scene and see that 40-foot cliff on that eastern side of the slump this year,” she said.
Merrell says the drop is in line with the slide’s multi-year progression.
“Its just over twice as far as it slumped the year before, which is consistent. We’ve been watching it since about 2016, and each winter it sloughs about twice as far as the year before,” she said.
Park crews have filled the slump with gravel for years to keep the road drivable. But last August, acceleration of the slide forced closure of the road and serious consideration of a permanent fix.
The NPS conducted an environmental review of a proposal to span the slide area with a 400-foot bridge anchored on solid ground on either side. That plan was approved last month.
There’s $25 million in the federal infrastructure law to pay for the first part of the estimated 2-year project, which also includes some other Polychrome area road work.
“Our partners at Federal Highways are getting ready to issue a request for proposals for contractors to submit their design build proposals for this bridge,” Merrell said.
Merrell says the timing should allow earthwork and site preparation to get underway this summer. Additional funds will be needed to construct the bridge, but how much depends on the selected contractor’s design.
Until the bridge is completed, Merrell says park visitor buses will only be traveling to the East Fork River, at mile 43.
“We’ve been working on making a safe spot for both transit and tour buses to turn around at the site,” she said.
Merrell says the only visitor access beyond mile 43 will be by air.
“You can fly to Kantishna. We’ve got several of our inholder lodges are operating as fly-in operations this year,” she said.
Merrell says the Park Service will not be operating its Wonder Lake campground near the end of the Park Road, but visitors can still apply for backcountry permits. She notes that Denali visitation is forecast to rebound to pre-pandemic levels this summer.
“Indicators are that we’ll likely be as busy as we were in 2019, which was a record-setting year for us,” she said.
Denali had over 6,000,000 visitors in 2019.
