GLENWOOD SPRINGS — Interstate 70 through the Glenwood Canyon reopened at about 3 p.m. Thursday afternoon, more than three days after a massive rock slide punched holes in the pavement and left all four lanes strewn with boulders.

Colorado Department of Transportation crews had been working to get one lane of traffic open in each direction since Monday morning. The slide occurred at about midnight Sunday.

One lane is open in each direction with a 14-foot width restriction; the speed limit is reduced to 40 mph through the canyon.

CDOT maintenance crews began clearing snow in the canyon early Thursday morning and making the final repairs necessary to get traffic moving again on the interstate, the main east-west thoroughfare through the Colorado mountains. It had been closed between Gypsum and Glenwood Springs, forcing motorists on a roughly 200-mile detour.

On Wednesday, a crew blasted a large, unstable boulder still perched 900 feet above the interstate. The blast brought down about a dozen larger boulders, and many smaller rocks that needed to be cleared away Thursday morning.

Repairs to the elevated roadway's drainage system and roadway patching in numerous places where boulders punched holes in the road surface are currently under way.

Crews set up traffic control cones, barrels, and signs on the interstate Wednesday, so the highway could be reopened quickly when the clean-up from Wednesday's work was finished.

Travel in just one lane in each direction will continue for weeks and months, as major repair work is still to be done. A CDOT engineer has estimated the repairs could cost upwards of $2 million.

The lengthy detour around the canyon apparently had some motorists seeking unlikely alternatives. Eagle County authorities were turning back motorists attempting to crive over Cottonwood Pass, which is not maintained for winter travel, and Pitkin County crews had to pull out two stuck trucks on the Fryingpan side of that route.