The Wyoming Department of Transportation and contractor Ames Construction have been working around the clock to rebuild the mountain beneath Teton Pass. They’ll continue working 24-hour shifts until winter decides they’re done for the season.
“The goal is to continue until the weather does not allow them to work anymore, which we're going to guess is going to be mid to late December,” John Eddins, district engineer for WYDOT District 3, told Cowboy State Daily. “They'll suspend operations and start again as early as possible in the spring, finish the project, and set the completion date for the project.”
The permanent solution for Wyoming Highway 22 will be finished by the end of July 2025, just over a year after the catastrophic collapse of the highway caused chaos that was quickly remedied by the opening of a detour road three weeks later.
“This was a textbook reaction to addressing a catastrophe,” Eddins said. “It makes me proud, and it’s very impressive.”
Digging Deep
The ongoing work on Teton Pass will be a permanent replacement for the section of the highway that failed June 8 when the mountainside underneath the road gave way. The fix is to rebuild it, this time better.
Eddins said a significant amount of planning and resources have gone into the project that started when the first cracks were showing in the pavement.
“One of the criteria we placed on the project is that it had to provide a 75-year design life and meet stability requirements,” he said. “It was an expensive project, but it meets that goal.”
The new Teton Pass will look exactly like the old one — the same highway occupying the same footprint. It should look and feel just as it did before the collapse for regular commuters.
The difference is what’s being done underneath the highway to ensure its structural stability. Phase 1 of the $40 million Teton Pass project involved drilling new supports into the bedrock of the mountain slope.
“We’ve drilled and set a whole series of micropiles, which are steel pipes that are set into the bedrock a certain depth on a 15-foot grid,” Eddins said. “Once those piles were set in bedrock, they were capped with a 3-by-3-foot concrete block. That’s what stabilizes and supports the weight of the fill.”
Ames Construction, the project contractor, is now placing lightweight foam glass aggregate fill across the area where the new highway will be built. The fill is enclosed in a system of baskets to give it additional stability.
Eddins said WYDOT wants to place as much of this “reinforced fill” as possible before winter fully sets in so it can provide additional stability during the mountain runoff next spring. That’s why road crews are working 24hours a day on the slope to complete the job.
“The more of that fill we can get placed, the stabler that detour gets,” he said. “When we get started next spring, it's urgent to get the project done, so it’s really urgent to get as much of that fill placed as we can this fall.”
Drain Gain
WYDOT engineers determined that the rapid melting of significant spring snowpack on the slope caused the June 8 collapse of Teton Pass. Water saturated the existing fill on the slope caused it to lose strength.
This lesson was taken to heart when designing the permanent solution for Teton Pass. In addition to the micropiles and reinforced fill, Eddins touted the project’s sophisticated drainage systems that should prevent this kind of failure in the future.
“As we're reinforcing the foundation, we're putting in drain systems to keep the water from building up in the fill,” he said. “We’ve incorporated horizontal drains to keep the water from building up in the field, as well as a sheet drain behind the field to drain water.”
Eddins said this design was a direct response to the June 8 failure. The contractor worked with WYDOT’s engineering team to ensure its success so everyone knew what to do from the start.
“We selected the contractor to work with this throughout the design process, telling us what's constructible and the most cost-effective way to attack it,” he said. “It was a unique contracting method for WYDOT where we had the contractor on the design team with us.”
Better Than Before
The Teton Pass project is scheduled to be completed by the end of July. Thanks to the detour, this should have little to no impact on the highway’s daily commuters.
“We're still carrying two-way traffic on the detour, and we'll continue to carry that traffic on the detour while we build the new permanent road,” Eddins said. “Once we get the permanent road done, we'll shift the commuters and the traveling public over on the new road while we clean up and regrade the area where the detour was.”
Eddins said WYDOT is cognizant of when there’s the most traffic on Teton Pass and will avoid disruptions during those hours as much as possible. The longest delay drivers could encounter at peak hours might be simple flag traffic as trucks move in and out of the construction zone.
Meanwhile, the detour road will be removed and the land reclaimed. Eddins sees this as an improvement for the mountain pass.
“We'll have a flatter slope on the north side of that highway,” he said. “It makes that side of the road safer.”
Within Its Lifespan
The permanent Teton Pass project will be a significant improvement over the highway as it was before its failure in June. The old road was built on native material without the significant ground improvements going into the new project.
Nevertheless, despite its structural failure, Eddins said the old Teton Pass fulfilled its 70-year lifespan. The failure has brought out the best of WYDOT’s engineering and construction capacities, and he said he’sincredibly proud of the results.
“We had the detour built and traffic on a paved two-lane road just under 27 days,” he said. “Then, we got the contract plans, specifications and everything together to develop this design in a matter of months and then got to work on it.
“I've worked for departments since 1988, so I've seen a lot of things similar to this. But this was a textbook response, and I’m very proud of what we’ve done.”
Contact Andrew Rossi at arossi@cowboystatedaily.com
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
