A rockslide on Interstate 70 near Glenwood Springs punched holes in a bridge and dumped boulders the size of semi trucks on the highway, closing a 17-miles stretch of the road Monday morning.

The slide occurred at midnight, just west of the Hanging Lake Tunnel in Glenwood Canyon, bring approximately 20 boulders onto the interstate, ranging in size from 3 ft to 10 ft in diameter. The largest is estimated to weigh about 66 tons.

The rocks have made holes in the elevated sections of the roadway—the largest being in the westbound lanes and measuring 20 ft by 10 ft. Another hole in the lower eastbound lanes measures 6 ft by 6 ft.

“There are a half-dozen other holes and dips in the roadway, as well as areas where rocks are embedded,” said CDOT spokeswoman Stacey Stegman. “Rocks are scattered over 100 yds of roadway.”

Also damaged are three sections, about 120 linear ft, of steel guardrail and 100 linear feet of median barrier. “The damage is similar to that resulting from a 2004 rockfall incident in the same area,” added Stegman.

While there is no estimate for a re-open time, Colorado Dept. of Transportation crews will blast and break up larger boulders, estimated to be the size of semis, today and continue work to assess when a portion of the roadway may be opened for travel, added Stegman.

CDOT will implement emergency contracting procedures and meet with contractors over the next couple of days as crews develop repair plans.