Teton Pass landslide: Was it preventable? When will it reopen? Here’s what we know
A 1-inch crack in a Wyoming highway soon turned into a gaping chasm as the road fell away in a landslide over the weekend, cutting off an essential route connecting Idaho with its neighboring state for commuters and tourists.
Officials said they first realized something was wrong with a section of Wyoming State Highway 22 over Teton Pass on Thursday after a motorcycle accident alerted law enforcement to cracks in the road.
They closed the highway for three hours to patch it after responding experts found the road at milepost 12.8 had begun sliding down the mountain 1 inch every hour Thursday, Wyoming Department of Transportation engineer Bob Hammond told the Idaho Statesman by phone.
By Friday, that movement had increased to 6 inches every hour. Early Friday morning, a mudslide occurred a couple of miles down the road at milepost 15, according to the transportation department. Then, at some point Friday night, the initial problem area “catastrophically failed” — meaning a sudden change from which recovery is impossible — when the road crumbled and collapsed in a landslide, the Wyoming Department of Transportation said in a statement. No one was hurt in either slide.
Crews are continuing to manage the mudslide at milepost 15 while experts create a plan to provide more drainage to the landslide area at milepost 12.8 by installing a box culvert that will help drain excess water in the soil, according to the department.
The Idaho Transportation Department said its crews and equipment have been assisting their Wyoming counterpart from the beginning. Seven ITD dump trucks hauled more than 80 loads of debris over the weekend, according to the agency.
“They called immediately; we started on our side and they started on theirs,” Lucas Richins, ITD operations foreman, said in a news release. “It was a good team effort.”
The Idaho Statesman looked at what caused the failure and what’s next for the highway.
How did the landslide happen?
Claudio Berti, director of the Idaho Geological Survey, told the Statesman that climate change and forest fires have caused more precipitation pattern changes in the past five to 15 years and, as a result, an increase in landslides.
Experts have been aware that the mountainside has been sliding for decades. In the past, however, it has always moved very slowly and only needed to be patched every 20 years or so, Hammond told the Statesman.
Hammond said the rapid acceleration of the slide was caused by an increase in groundwater oversaturating the soil to create a “very slick” surface area. The increase in groundwater was likely from snow melting in the spring and draining in that area, but no one yet knows why the melt fed into an area near the roadway this year when it hadn’t previously.
Hammond said he doesn’t think the landslide could have been prevented.
“We have lots of landslides we work on all the time,” Hammond said. “This wasn’t a major concern at all. It hadn’t really shown any strong instability, but things changed, and they changed quickly.”
Why didn’t this get fixed earlier?
Berti, director of the Idaho Geological Survey, said landslides are expected in places like the Teton Pass, which has been sliding for decades.
“This was simply going to happen at some point,” Berti said.
But finding a solution to slipping roads is “not as easy as one would hope,” Berti added. Often, there is no safe place to put a mountain road. Tunnels are sometimes an option, but they are costly and may come with their own set of risks.
Berti said officials often elect to minimize the dangers by simply monitoring an area and continuing to patch it.
When will the road reopen?
Hammond said the road will be fixed eventually, but officials are still in the process of determining when they can reopen it.
Geologists and engineers are “evaluating the area and putting together a long-term plan to rebuild the road,” the Wyoming Transportation Department said.
Hammond is hoping it will be before the end of the year but said it’s too soon to say.
Fortunately, there will be a short-term fix coming for those who need to access the area sooner. Construction workers are building a temporary road at the landslide site that people will hopefully be able to access within the next two weeks, Hammond said.
Until then, the Wyoming Department of Transportation is asking drivers to take a detour using U.S. Highway 26 through Swan Valley into the Snake River Canyon.
The department said its next step is flying the area in a survey plane and conducting “geological drilling in preparation for the reconstruction.”
This story was originally published June 11, 2024 at 4:00 AM.
