‘Catastrophic’ Teton Pass Failure Had Been Building For Decades

The closing of Highway 22 over Teton Pass is now a week into reality. Early results are in: This is going to be painful.

As geologists drill onsite for soil samples to get a feel for how loosey-goosey the subsurface is, crews above ground have been cutting down trees and trucking in fill to make way for a reroute just inside the curved portion of roadway that slid away.

Meanwhile, another Wyoming Department of Transportation team is busy 2 miles west building a box culvert trying to coax mountain runoff downslope at the scene of an unrelated mudslide.

Work is intense and progressing around the clock. Officials are hopeful the temporary fix will make the road traversable again within a couple weeks, which would be good news for Fourth of July holiday travelers.

Bye Pass

Hindsight spurs relief over what could have been a disaster. The section of highway at milepost 12.8 that eventually fell away was first called to the attention of WYDOT on June 6 when cracks in the pavement initially appeared, causing a motorcyclist to crash.

The plan, at that time, was to send a road surface team up to make yet another seal on the troublesome spot. Engineers and geologists have known for decades about the sluggish landslide. These slow-motion shiftings and oozings of large earth masses are common in mountainous areas. A similar landslide happened in the Snake River Canyon in 2011.

Road crews affected a fix but were concerned about its effectiveness. The pass was reopened, but authorities kept a careful on eye on the situation.

Then another problem. Rapidly warming temperatures combined with recent rains had another section of mountain slip sliding away. This time the problem was a giant mudslide at milepost 15 at Talbot Canyon on June 7. Again, another known area where terra firma sometimes melts away in the spring.

As the pass was closed for the second time in as many days, highway crews noticed the cracks at milepost 12.8 were widening. This was not the usual millimeter shifts they would encounter many springs. This was something far worse.

WYDOT crews did what they could that Friday night to shore up the area, but when they returned Saturday morning, June 8, their worst fears were realized. The road had failed. The mountain had slid. If not for the closure of the highway because of the mudslide down the road, the landslide could have killed someone.

“Wow! Teton Pass broke. May be a short-term solution here but can’t imagine this is fixable by winter,” commented world-famous snowboarder and local Travis Rice on social media.

A long-term solution might be months, or possibly years, in the making, but the quick (and safe, WYDOT points out) Band-Aid should be ready in weeks.

The entire corridor is scheduled for a major overhaul by the Federal Highway Administration and Federal Lands Highways in coordination with multi-jurisdictional assistance from WYDOT, the Idaho Department of Transportation, Bridger-Teton National Forest, Caribou-Targhee National Forest and Teton County, as well as Teton County Idaho.

An exhaustive study was finalized just this past January.

Teton Impasse

Teton Pass has always been a bear. Since the first Shoshone pony trotted over it in the early 1800s, ensuing wagonloads in the latter part of that century, and lumbering Airstreams today, traversing the high mountain pass is a white-knuckle ride not soon forgotten.

The Jackson workforce commutes it daily, requiring more frequent fill-ups and brake jobs than the average car owner. It’s a key corridor serving to link bedroom communities of Victor and Driggs, Idaho, with Jackson.

Inbound tourism traffic from West Yellowstone and Idaho Falls will have options available that do not use Highway 22 over Teton Pass, but those alternatives will further strain an already busy North and South Highway 89/191.

The aforementioned Teton Pass Corridor Study of 2024 recognized the mountain pass as the lifeblood of the socioeconomic juggernaut Jackson is. A “critical” connector of two communities in different states but same county names: Teton.

“While the corridor stretches 24 miles between these two community centers, the 16-mile section of highway between Wilson, Wyoming, and Victor, Idaho, is currently grappling with substantial safety, access and capacity challenges,” the report reads. “The volume of recreational, commercial and commuter traffic has risen in conjunction with the overall economic and demographic expansion of the region.”

Latest 2020 census numbers put the combined population of the twin Teton counties at 36,000, up 47% from 2000’s 24,467. COVID brought even more by droves. Those numbers are likely much higher in 2024.

Among the estimated 20,086 workers employed in Teton County, Wyoming, more than half commute from outside the county. How many from Teton Valley, Idaho, (comprising Victor, Driggs, Tetonia, et al) is difficult to pin down, but the latest traffic counts from 2020 show 10,307 vehicles per day over the pass. In summer peak, that number is probably more like 15,000 today, according to WYDOT.

Melting Mountain

Engineering has come a long way since the first road over Teton Pass. That one in 1901 cost $500. The first auto wouldn’t come across until 1914.

The wagon road was so steep, teamsters would drag logs behind their rig to act as brakes or find a smaller downed tree at the top and run that clear through the spokes of the wagon’s back wheels to lock them up for the descent.

Motorists didn’t have it much easier. In those early days of the Model T Fords, drivers often had to climb the steepest sections in reverse because those models did not have a fuel pump. Gravity was required to feed the engine gas.

The narrow, one-lane road included 16% grades in some sections. Downhill motorists were required to pull over and give way to uphill-bound drivers because if those stopped, they would not be able to get going again.

Local surveyor Otho Williams laid out the Teton Pass Road in 1900. It remained no more than a wagon road with an endless repetition of switchbacks. In 1918, the Bureau of Public Roads completed a new road over the pass headed by engineer R.A. Ogden. For the most part, it followed the alignment of the old wagon road.

Several years later in 1925, the U.S. Forest Service allocated $12,000 to surface Teton Pass Road. In 1932, the Bureau of Public Roads initiated a major upgrade of the road. It was widened from 8 to 18 feet, surfaced and some of the steeper sections were reduced in grade by 3% to 4%. The road was oiled for the first time in 1940 to keep the dust down.

Still, the pass would close all winter. A collection would be taken up by valley residents every spring for the $400 it took to plow the road open again.

Beginning in 1938, the state took over regular plowing of the road during winter, but that did not go smoothly. Regular snowslides would hamper efforts finally prompting the highway department to walk off the job on New Year’s Day in 1940.

Gov. Nels Smith was petitioned for help. When it didn’t come, angry Jackson residents broke into the state’s facilities and commandeered the plow trucks themselves.

A Pair Of Bad Ideas

Constant avalanches, particularly from Twin Slides and Glory Slides, plagued pass drivers for decades. When the highway department began to realign the Teton Pass highway in 1967, they included plans for a bridge spanning the most avalanche-prone area — a chute off the south-facing Mount Glory.

Dr. Shieh W. Shen of the Engineering Research Department at Colorado State University was enlisted to design the project. Confident his bridge could withstand anything Glory could throw at it, construction began in 1969.

Just before the bridge deck could be added as the final touch, an avalanche roared down Glory on Jan. 22, 1970, and took the entire structure with it. No effort was ever made to revive the project.

Ideas about a tunnel have met with a similar lack of inertia. A 2013 study found two major roadblocks — cost and quakes.

Teton Pass’ “Precambrian-aged gneisses and schist rock are extremely hard and durable and, taken by themselves, would be acceptable material to bore a tunnel through. However, the fault that created the Tetons is still active and poses seismic concerns,” reads the feasibility report. “The physical geology of the area, with its active faults, known earthquakes and geothermal activity, would most certainly require extensive investigation and a more complex design.”

In addition, costs to build (approaching $1 billion) and maintain (an estimated $400,000 annually) a 1.5-mile tunnel section are most assuredly non-starters.

“At this time the costs are too high and there are too many variables and unknowns to justify the continued investigation of constructing a tunnel through Teton Pass,” the report summarizes.

Slippery Slope

When contemplating a multiuse pathway/trail alongside Highway 22 in the 3-mile section between the summit and Coal Creek (the section that includes milepost 12.8 where the landslide occurred), officials thought the notion impractical for the exact reasons the road failed last weekend.

“[T]o complete the paved multi-use trail will be very difficult from a landslide, wetland and engineering standpoint,” engineers stated.

Experts say the highway section — called “The Big Fill” for the amount of dirt it took to stabilize it originally and have it hold up for now 55 years — is about all one could ask. That lifespan is better than might be expected of the average road.

WYDOT is now tasked with doing what it did in the late 1960s to build the road — drill pilings down to bedrock, add fill and perhaps retaining walls until the area is stabilized.

Once WYDOT’s geology department signs off on the prescribed remedial action, expect work to accelerate to the point where no amount of money or manpower will get a fix done quicker.

Man and machine are battled-tested against this mountain. Occasionally, Mother Nature wins, but in the end, the tiny humans and their diesel-belching bulldozers always adapt and overcome.

Jake Nichols can be reached at jake@cowboystatedaily.com.