The Dalton Highway and the Trans-Alaska Pipeline are companions that rank among Alaska’s most vital and iconic pieces of infrastructure. The pipeline exists because of the highway. The highway exists because of the pipeline.  

What threatens one, threatens the other. 

The highway is being pummeled by flooding, staggered by thawing permafrost and confronted by monstrous underground landslides known as frozen debris lobes. 

Since 2015, the highway has undergone a half dozen major overhauls to bolster it against natural disasters triggered by climate change. 

The highway has been elevated to keep it from being submerged by flooding rivers engorged by heavy rains and increasing snow melt. It has been reinforced against thawing permafrost that has left it so weakened in places it could threaten the heavy 18-wheelers that rumble its path daily. And a mile long section has been rerouted to keep it from being swallowed by an underground debris lobe slowly pushing toward it. 

The codependence between the highway and pipeline is such that if one fails the other faces failure, said Larry Persily, a former federal coordinator for Alaska gas projects. 

“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.

Since a massive flood on the Sagavanirktok, known as the Sag, in 2015 closed the highway for 28 days and prompted two disaster declarations by the governor, Alaska transportation engineers have been checking off a long list of increasingly urgent and costly projects designed to shield the highway from climate-change related catastrophes.

One of the projects, triggered by the severe flooding of the Sag in 2019, was recently completed at a cost of $70 million in state and federal funds. The mostly gravel roadway, which runs less than a mile from the pipeline and the river, was elevated between seven and ten feet to keep it above the new flood levels of the Sag.

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.

The Impacts of Climate Change

Alaska is among the fastest warming regions on Earth and is warming faster than any other state, according to the Fourth National Climate Assessment published in 2018. By the middle of the century, the highest daily maximum temperature could increase between 4 and 8 degrees Fahrenheit.

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, which is one of the northern-most roads in the world, begins just north of Fairbanks and runs for 414 miles to Deadhorse on the shores of 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. 

Trucker Threats

Robert Myers is the chair of the Transportation Committee for the Alaska State Senate and a trucker on the Dalton. “The hazards are changing seasonally and becoming more noticeable,” said Myers, who drives a Peterbilt truck with a 600-horsepower Cummins diesel engine. 

The potential of floods inundating the highway and causing road closures along with thawing permafrost turning the road into an obstacle course are never far from the minds of truckers, he said. 

“There are more issues now with rain on the North Slope and permafrost in the south,” Myers said. 

Flooding can stop big rigs dead in their tracks when the highway is underwater.  Ruts caused by thawing permafrost can make the highway so rough that truckers have to creep along at 10 miles an hour to keep from losing control, he said. 

“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 to point out that haul road truckers face hazards other than 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.”

Transportation officials are effusive when describing the pastoral route the Dalton takes once it crosses the Arctic Circle.

“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 Hit 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 on the north slope of the Brooks Range and flows 180 miles north to the Beaufort Sea near Prudhoe Bay. The river parallels the highway and pipeline for 35 miles, never being more than a mile away from 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 proclaimed the flooding a disaster for the entire North Slope Borough and the Dalton Highway. Water swirled around the pipeline and prompted emergency measures to build dams to deflect the current away from the four-foot diameter conduit that carries an average of 20 million gallons of oil a 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 project engineer who has supervised several of the Dalton Highway remediation projects, said the 2015 deluge exposed the vulnerability of the Dalton to flooding and produced lessons that would be applied to future roadwork on the highway.

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. 

There was a time soon after the highway and pipeline were built that the main channel of the Sag River was more than a mile from the pair. 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 the 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. That information is then used to calculate how much the roadway must be elevated to keep it safe from flooding. 

“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. Along the southern stretches of the Dalton, the segment of highway DeBernardi said he is most familiar with, mitigation projects are incorporating more insulating material.

To keep the ground along the highway cold, engineers use one-inch foam boards that provide as much insulation as one foot of soil, or they increase the amount of soil packed along the highway embankment. 

Along with those two mitigation measures, engineers have developed another strategy for keeping the ground cold: instead of packing the shoulder of the highway solid, they line it with loosely laid rocks to allow cold air to circulate. The process is called Air Convection Embankment, an experimental technology embraced by the transportation department that could provide a more efficient and cost-effective means of insulating the highway. 

A Convergence of Extremes

Although the flooding of 2015 was an exceptional occurrence, it presaged the flooding and increased permafrost thaw that has plagued the Dalton for the last six years, said Rick Thoman, a climate specialist with the Alaska Center for Climate Assessment and Policy at the University of Alaska, Fairbanks.

The fall of 2014 saw rainfall at 125 percent of normal levels according to figures kept by the climate center. That water percolated into the ground and began migrating toward the river. The above average pulses of rainwater from the fall reached the river that spring when temperatures soared into the high 70s, melting extraordinary amounts of snow to swell the river. 

That was a convergence of extremes, Thoman said. But it’s indicative of a climate change induced trend. Rain along the Brooks Range that feeds the Sag and other rivers has been increasing, and spikes in springtime temperatures that hasten snow melt have become common, swelling rivers to flood stages rarely recorded in the past. Earlier warming and later freezing has hastened permafrost thaw so that the ground supporting the Dalton has become less stable.

“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 raising the highway is an occasional, major undertaking, filling pot holes is a common chore made more vexing by climate change. Despite efforts to upgrade sections of highway, its gravel surface is still plagued with potholes, ruts and a rough surface, transportation officials lament.

“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 work to fortify the Dalton against flooding was wrapping up in 2018, the first of several projects to address the consequences to the highway of thawing permafrost were getting underway. 

Jeff Currey, a Northern Region materials engineer, said about 60 percent of the work on the Dalton is now related to thawing permafrost because of 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

For now, Currey said the threat to the stability of the highway caused by thawing permafrost 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.

The Dalton faces a two-prong threat from thawing permafrost, according to a 2021 study published this year in the journal The Cryosphere. 

Researchers, focused on a section of the highway about 10 miles south of the Prudhoe Bay, discovered that thawing permafrost not only will cause more destabilization directly beneath the highway but will increasingly extend out from the side of the roadway.

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.

In the past, the highway faced little threat from thawing permafrost when the soil temperatures kept the ground as hard as a rock at minus 8 degrees Celsius. But gradual warming has made the Dalton much more susceptible to disturbances, the study said. As ground temperatures approach near zero degrees, thawing will accelerate and the roadway will become much more unstable. 

“The thermal buffering of the lower shoulder is not sufficient anymore to prevent strong thawing in the embankment,” the study said.

Vladimir Romanovsky, a permafrost expert at the University of Alaska, Fairbanks and a co-author of the study, said the research suggests that continuing to operate critical infrastructure in permafrost areas, such as the Dalton Highway, will be challenging and, in some cases, fruitless.

“The thawing is triggering settlement of the shoulders of the highway; the beginning of the destruction of the highway,” he said.

Romanovsky, who has been traveling the length of the Dalton since 1992 for his research, said the settlement caused by thawing permafrost leads to abrupt rolling and heaving of the highway. 

“It’s like driving on a washboard,” he said. “You drive a ways and dip and bump, drive; dip and bump.” 

There are no good, cheap solutions, he said.

“It’s not getting better, it’s getting worse,” Romanovsky said. “That’s the future.”