The Dalton Highway and the Trans-Alaska Pipeline are companions that rank among Alaska’s most vital and iconic pieces of infrastructure. The highway is what made the pipeline possible. The pipeline is what makes the highway possible.
What threatens one, also threatens the other.
The flooding is causing major damage to the highway. It is also being hampered by thawing Permafrost.
To protect the highway from natural disasters caused by climate change, half a dozen major upgrades have been made to it since 2015.
To prevent flooding rivers from becoming engorged by heavy rains or increasing snow melt, the highway has been raised. It has been strengthened against thawing snow melt that has left it in such weak places that it could be threatened by the heavy 18-wheelers who plow its path daily. It has been rerouted for a mile to avoid it being swallowed by underground debris lobes slowly pushing towards it.
Larry Persily, a former federal coordinator of Alaska gas projects, stated that the highway and pipeline are so interdependent that one can fail the other.
“They are inexorably linked at the hip; not just at the hip but hundreds of miles of the hip,” he said. “The interior of Alaska’s climate is changing, and those changes are felt equally by the highway and pipeline.”
At a time when flooding on the Sagavanirktok River in northern Alaska’s Brooks Range has driven the owners of the pipeline to fortify it against the restless river, Alaska Department of Transportation and Public Facilities officials have pumped millions of dollars into projects to keep the highway dry and stable.
Alaska transportation engineers have been completing a long list, increasingly expensive, of urgent projects to protect the highway from climate-change-related catastrophes since the 2015 floods on the Sagavanirktok (also known as the Sag) closed the highway for 28 consecutive days.
One of these projects was triggered by the 2019 severe flooding of the Sag. It was completed recently with $70 million in federal and state funds. The gravel road, which runs less that a mile from the river and the pipeline, was raised between seven and ten feet in order to keep it above flood levels.
William Russell, superintendent of the Department of Transportation’s Northern Region Maintenance and Operations Division, has witnessed the Sag’s ferocity and the push by the transportation agency and Alyeska Pipeline Service Company, a syndicate of oil companies that own and operate the Trans-Alaska Pipeline System (TAPS), to defend the roadway and pipeline against flooding.
“The high-water flow is a fairly new phenomenon,” he said. He described the recent flooding as the most frequent and worst he’s seen during the 20 years he’s worked on the northern section of the highway, which for most of its half century of existence sat level with the tundra and unmolested by flooding.
“We understand the advantages to adapting to the flooding,” he said.
Climate Change: The Impacts
According to the Fourth National Climate Assessment published 2018 in 2018, Alaska is one of the most rapidly warming regions on Earth. It is warming faster than any other country. The highest daily temperature could rise between 4 and 8 degrees Fahrenheit by the middle of this century.
A 2016 report published in the Proceedings of the National Academy of Sciences focused on the consequences of climate change to Alaskan infrastructure estimated that impacts to public infrastructure in the state will total about $5 billion by century’s end. Roads, runways, railroads, buildings and pipelines of all sorts are becoming more susceptible to damage from flooding and thawing permafrost.The report found that flooding will account for about 45 percent of the damages, and thawing permafrost will be responsible for 38 percent of the havoc—the two biggest threats to the Dalton Highway.
The rapidly changing conditions increase the vulnerability of the Dalton and all of Alaska’s infrastructure by enhancing environmental stressors, said Doug Goering, dean emeritus of the University of Alaska at Fairbanks’ College of Engineering and Mines.
“Certainly there will be increasing maintenance demands to keep the highway stable,” he said.
The Dalton Highway, one of the most northern roads in the world, starts just north of Fairbanks. It runs 414 miles to Deadhorse, on the shores the Arctic Ocean. It’s a pride and joy of Alaska’s transportation department, but one of its most troublesome highways to maintain.
The traffic on the highway includes a mix of tourists, recreationists, hunters and researchers, but it is dominated by a steady stream of large commercial trucks—an estimated 100 18-wheelers loaded with 2,500 tons of fuel, equipment and supplies bound for North Slope communities and the Prudhoe Bay oil fields thunder up the road daily.
The Dalton Highway, known as the Haul Road, was originally constructed by Alyeska in 1974 to support the development and construction of the pipeline and to service the oil fields on Alaska’s North Slope. It’s now owned and maintained by the State of Alaska.
Robert Myers, the chair of Alaska State Senate’s Transportation Committee, is a trucker on Dalton. “The hazards are changing seasonally and becoming more noticeable,” said Myers, who drives a Peterbilt truck with a 600-horsepower Cummins diesel engine.
Truckers are always aware of the possibility of flooding the highway, causing road closures, and the possibility of thawing permafrost turning roads into obstacle courses.
“There are more issues now with rain on the North Slope and permafrost in the south,” Myers said.
Flooding can make it impossible for big trucks to continue driving if the highway is submerged. He said that thawing permafrost could cause ruts on the highway, which can make it so dangerous that truckers must travel at 10 mph to avoid losing control.
“The Dalton is a major factor in the state’s economy so any time something stops or slows the flow of truck traffic it has consequences,” Myers said.
Myers is quick and clear to point out that haul-road truckers face hazards beyond flooding and thawing Permafrost.
“To top off the changing conditions we’re seeing in the summer and winter, we have to deal with wildlife issues,” he said. “For some reason caribou don’t understand they shouldn’t walk out in front of a big truck.”
When describing the pastoral route taken by the Dalton once it crosses the Arctic Circle, transportation officials are enthusiastic.
“The last 50 miles of the Dalton Highway are built on top of an expansive tundra landscape that spills out of the 126-million-year-old Brooks Mountain Range and heads toward the shores of the Arctic Ocean,” the agency wrote in a highway construction update last year. “This treeless country is covered in snowy darkness, low sun, and Northern Lights much of the year. In the summertime it transforms into rolling grasses, wildflowers, soggy bogs, and wild rivers under constant daylight.”
One of the largest floods to ever strike the highway
That idyllic scene was shattered in 2015 when the spring breakup on the North Slope triggered severe flooding of the Sagavanirktok, which means “strong current” in the Iñupiaq language. The river originates at the Brooks Range’s north slope and flows 180 miles north towards the Beaufort Sea near Prudhoe Bay. The river follows the pipeline and highway for 35 miles. It never travels more than a mile between the two.
Engineering consultants described the 2015 flooding of Sag as being on “a larger scale than the area had ever seen.” Water washed out several sections of the highway and inundated Deadhorse and surrounding areas.
Then-Gov. Bill Walker declared the flooding a disaster for all of North Slope Borough, and the Dalton Highway. Water gathered around the pipeline, prompting emergency measures to build dams in order to divert the current away. The four-foot diameter conduit carries an average 20 million gallons per day.
“There’s no doubt that (was) one of the most dramatic events in the highway’s history,” transportation department public affairs officials later wrote about the event.
Madrilena Bradley, a transportation engineer who supervised many of the Dalton Highway remediation programs, stated that the 2015 flooding exposed the Dalton to flooding. She also learned lessons that will be applied to future roadwork.
After the birth of the highway in 1974, the road was level with the tundra, and for decades there weren’t any problems, she said. But not now. “The Sag has changed course and the water is coming closer and closer,” she said.
The main channel of the Sag River was not more than a mile from the pair when the pipeline and highway were constructed. But the meandering Sag, defined as a “braided” river because of its network of crisscrossing smaller channels, has drawn closer to the highway and pipeline over the years.
Reengineering Dalton Highway
Raising the highway with tons of gravel requires significant engineering calculations, said Lance DeBernardi, a senior project engineer at R&M Consultants who has done design work on the Dalton in conjunction with the transportation department.
There’s a thorough hydrologic and hydraulic analysis performed as the foundation for designing remediation measures. Precipitation amounts—snow and rain—are calculated using historical data and modeling to get an idea of how much flooding a section of the highway may experience, he said.
DeBernardi said it’s common now for engineers to expect long term increases of 20 to 25 percent in mean annual precipitation. The information is used to calculate the amount of roadway that must be raised to keep it from flooding.
Keep Environmental Journalism Alive
ICN provides award winning climate coverage without charge or advertising. To continue, we rely on donations from readers like yourself.
You will be redirected to ICN’s donation partner.
“When starting any road project, we first reach out to maintenance and operation personnel to discuss their observations of precipitation and climate characteristics and trends within the project corridor,” DeBernardi said. DeBernardi says he is most familiar about mitigation projects along the southern sections of the Dalton.
Engineers use one-inch foam boards to keep the highway ground cold. They also increase the soil density along the highway embankment.
Engineers have developed a second strategy to keep the ground cold. Instead of sealing the highway shoulder with concrete, they cover it with loosely arranged rocks that allow cold air circulation. Air Convection Embankment is an experimental technology that the transportation department has adopted to insulate the highway. It is more cost-effective and efficient than traditional insulation.
A Convergence between Extremes
Although 2015’s flooding was an extraordinary event, it presaged the flooding and increased Permafrost Thaw that have plagued the Dalton for six years, according to Rick Thoman, a climate specialist at the Alaska Center for Climate Assessment and Policy, University of Alaska, Fairbanks.
According to climate center figures, 2014’s fall saw rainfall at 125% of normal levels. The water percolated into ground and began moving toward the river. The river was flooded by the above-average rainwater flows from the fall. It reached the river in the spring when temperatures reached the high 70s.
Thoman stated that it was a convergence or extremes. But it’s indicative of a climate change induced trend. Rain has been increasing along the Brooks Range, which feeds the Sag, and temperatures have risen to speed snow melt. This has led to rivers swelling to flood stages that were not possible in the past. The ground supporting the Dalton is now less stable because of earlier warming and later frost.
“Changes in the environment are so far out ahead of us we wonder, ‘Oh man, are we ever going to get a handle on this,’” Thoman said.
While it is possible to raise the highway, it is not a major undertaking. However, filling potholes can be a tedious task, made more difficult by climate changes. Transportation officials lament that, despite attempts to improve portions of the highway’s gravel surface, there are still potholes, cracks and rough spots.
“Maintenance crews stretched thin by years of budget cuts are facing a wetter, warmer climate that is making it increasingly difficult to keep the road in decent shape,” according to a Northern Region transportation department bulletin.
As the Dalton was being fortified against flooding in 2018, the first of several projects to address permafrost-thawing highway effects were underway.
Jeff Currey, a Northern Region materials engineering engineer, stated that about 60% of the work on Dalton is now related the melting permafrost due to warming temperatures.
“We looked at climate projections out to 2050 and saw what was in the future and what was going to be needed for stability of the highway,” he said.
A Two-Pronged Threat
Currey says that for the moment, the permafrost thawing threat to highway stability is under control. But, he said, thawing permafrost will “require frequent maintenance” to keep sections of the highway from sinking as warmer temperatures cause the once rock-hard permafrost to turn soft.
The transportation department added thermal berms alongside the Dalton on a stretch of highway between Fairbanks and Coldfoot to slow “uneven thaw settlement” under the roadway in 2018.
In 2019, the department began developing plans “to address the settlement and other embankment failures” along a stretch of the highway midway between Fairbanks and Prudhoe Bay.
According to a 2021 study published in The Cryosphere, the threat to The Dalton from melting permafrost is two-prong.
Researchers examined a section of the highway that runs south of Prudhoe Bay. They found that the highway’s permafrost would expand outwards from the roadway’s side.
Rather than happening gradually as long-term climate change sends warmth down into the soil, the thaw is expected to happen in two phases, “an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming,” according to the study.
The highway was not at risk from melting permafrost in the past because the soil temperatures were below minus 8 degrees Celsius. The study concluded that the Dalton has become more susceptible to disturbances because of the gradual warming. The roadway will become more unstable as the ground temperature approaches near zero degrees.
“The thermal buffering of the lower shoulder is not sufficient anymore to prevent strong thawing in the embankment,” the study said.
Vladimir Romanovsky, a University of Alaska, Fairbanks permafrost expert and co-author of this study, stated that it will be difficult and sometimes impossible to continue operating critical infrastructure in permafrost regions like the Dalton Highway.
“The thawing is triggering settlement of the shoulders of the highway; the beginning of the destruction of the highway,” he said.
Romanovsky, a researcher who has been travelling the length of Dalton since 1992, stated that the settlement caused due to thawing permafrost causes abrupt rolling and heaving.
“It’s like driving on a washboard,” he said. “You drive a ways and dip and bump, drive; dip and bump.”
He stated that there are no cheap, good solutions.
“It’s not getting better, it’s getting worse,” Romanovsky said. “That’s the future.”
Source: Inside Climate News