AUBURN – A section of Route 136 washed into the Androscoggin River Wednesday and highway officials say it will take two days and millions of dollars to fix.

A 120-foot section of riverbank at the Auburn-Durham town line collapsed at about 4 p.m., taking away a chunk of the road shoulder with it.

“About 20 feet of the shoulder slid into the river, leaving the guardrail hanging there in the air,” said Department of Transportation Spokesman Mark Latte.

Highway crews went to the scene and quickly closed down Route 136, one of the busiest throughways in the area.

Auburn police also went out and began the process of diverting the heavy commuter traffic from Route 136 onto Pownal, Stackpole and Jordan School Roads.

Latte had some quick advice for those who use Route 136 on a regular basis: find a new way to travel for the next couple days, or expect delays.

“That’s the main connector between Auburn and Freeport, obviously,” Latte said.

Repairs will begin Thursday morning when crews will start to rebuild the bank, repair the road and lay down new pavement. In the most optimistic scenario, Route 136 could be open again by Friday night.

The work will be done by the DOT and Shaw Brothers Construction of Gorham. Latte did not know how much the repairs will cost, but predicted it will be in the millions of dollars.

The trouble on Riverside Drive began, he said, with something known technically as circular slope failure, which occurs when a stream or river slices into the lower half of a bank, undercutting it and causing it to collapse.