ANCHORAGE, Alaska (AP) — Alaska highway workers have moved the Dalton Highway away from a gigantic mass of frozen debris that is oozing down a hillside so that the road doesn't get T-boned by the so-called blob.

The roughly mile-long (2 kilometer-long) frozen debris lobe — consisting of dirt, ice and trees — threatens to bulldoze away a section of the road more than 200 miles (322 kilometers) north of Fairbanks in three to four years, transportation officials said.

Motorists were re-routed onto the new gravel road starting Aug. 31, the Anchorage Daily News reported Friday.

The project cost the state about $2 million, said Jeff Currey, a materials engineer with the Alaska Department of Transportation and Public Facilities.

The lobe is essentially a slow-motion permafrost landslide and measured up to 90 feet (27 meters) thick and 850 feet (259 meters) wide last year.

The work means it will be 20 or so years until the blob may threaten the road again.

Most motorists who depend on the highway are truck drivers delivering supplies to the North Slope oil fields —which in turn pays for most state services — making the highway a critical conduit for Alaska's economy.

The state had considered many options to stop the lobe from encroaching the two-lane highway — including blowing it up, building a bridge around it and dismantling it before deciding to realign 4,000 feet (1,219 meters) of road.

The old road is still in place as an experiment designed to inform transportation managers about the threat other lobes across the state could cause.

"Learning about the behavior of these things will be useful in the future," Currey said.

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Information from: Anchorage Daily News, http://www.adn.com