The Denali Park Road has a slump in it. The road was cut into the rocks 90 years ago, and a section at Mile 45 in Polychrome Pass, in an area that is known as Pretty Rocks, is built over an underground rock glacier. The existence of the glacier was unknown at that time, but it has been melting at an accelerating rate the past three years.
In 2018 the road was dropping an inch a month, by 2019 that had grown to an inch a day. This August, the road has been dropping over a half inch an hour. More than 100 dump truck loads of gravel were dropped over this span every week this summer, but even that proved pointless, and the Park Road was closed to traffic at Mile 43 in August. The landslide has moved far enough down the hillside to expose the ice below the roadway.
Winter should put the freeze into the ground once again, so that the road can be used early next spring, but the plans are for the road to be closed for all of the summer of 2022. There is solid rock on either side of the glacier, so a bridge will be anchored into those to span the slump zone.
Photo and time-lapse credit: NPS