Maintaining roads as permafrost thaws …
Editor's note: second of two reports on the challenge of engineering roads in the circumpolar north in a warming climate.
Some 200 big rigs travel the Dalton Highway on an average day to bring supplies to the giant Prudhoe Bay oilfield complex. All that trucking requires regular repair work along the 414-mile mostly gravel road – an ongoing and costly challenge that could become even more if road-building technologies developed to protect permafrost under roadways no longer work.
“In Alaska and in the Arctic, the air temperatures are going up,” says Jeff Currey, an Alaska Department of Transportation engineer. “But they not going up in the summertime so much as they’re going up in the wintertime. That’s when we need the cold temperature to make these technologies work, to drive that cooling of the permafrost.”
Jeff Currey, a materials engineer, has worked for decades building roads with air-circulating and thermosyphon technologies to keep the permafrost underneath from thawing. That makes soil under the roadbed sink and settle, creating dips and humps that require costly repairs. But Currey and other engineers say there’s now growing concern that warming in the far north may make those technologies ineffective here.
“We’re seeing that some of these techniques that we have become accustomed to, that are working very well for us, may cease to work maybe some time mid-century, because of the temperature changes,” he said.
Billy Connor directs the Alaska University Transportation Center at UAF’s Institute of Northern Engineering. He says concerns about how long permafrost-preserving technologies will work in this part of Alaska came up again last month in a talk about the $54 million project to rebuild a stretch of the Dalton Highway about 75 miles north of Fairbanks.
“We asked the question – if it continues to warm, at what point will these technologies cease to work?” Connor said.
Currey says while engineers study new solutions, the existing technologies will continue to be used – farther north.
“A technology that works well in Fairbanks now will probably still work well in the Brooks Range sometime into the future,” he said.
Currey says some answers may come from data that’ll be generated by sensors to be buried in and around the Dalton project site.