Illustration: Sam Dodge for Bloomberg
A critical artery is threatened by thawing permafrost.
Aug. 2, 2016 (Bloomberg) -- For seven decades, the Alaska Highway has mesmerized adventure-seeking travelers. In one breathtaking stretch through the Yukon, glacier lakes and rivers snake through aspen forests and rugged mountains that climb into the clouds.
In recent years, though, a new sight has been drawing motorists’ attention, too, one they can spot just a few feet from their cars’ tires. Bumps and cracks have scarred huge swathes of the road, with some fissures so deep a grown man can jump in and walk through them. Scientists say they’re the crystal-clear manifestation that permafrost -- slabs of ice and sediment just beneath the Earth’s surface in colder climes -- is thawing as global temperatures keep rising.
In some parts of the 1,387-mile (2,232 kilometer) highway, the shifting is so pronounced, it has buckled parts of the asphalt. Caution flags warn drivers to slow down, while engineers are hard at work concocting seemingly improbable solutions: inserting plastic cooling tubes or insulation sheets, using lighter-colored asphalt or adding layers of soccer-ball sized rocks -- fixes that are financially and logistically daunting.
“It’s the single biggest geotechnical problem we have,” said Jeff Currey, materials engineer for the northern region of Alaska’s Department of Transportation. “The Romans built roads 2,000 years ago that people are still using. On the other hand, we have built roads that within a year or two, without any maintenance, look like a roller coaster because they are built over thaw-unstable permafrost.”
