Update: Pass is officially "open". CDOT is alternating single-lane traffic around slide, and says to "Expect long delays, especially between 7AM and 7 PM during cleanup work." Read their official statement here.
The closure of Highway 133 south of McClure Pass due to a rockslide will likely last throughout the week. Falling boulders including one rock as big as a dump truck forced the closure Sunday morning.
The incident means motorists traveling between Paonia and the Roaring Fork Valley must take a detour of about 140 miles over Grand Mesa.
The Colorado Department of Transportation said the highway was closed around 9:30 a.m. Sunday at mile marker 29 about 13 miles south of the pass and just north of Paonia Reservoir after about seven or eight rocks fell onto the road and into a ditch.
The largest rock was 30 by 15 by 10 feet in size, with another one about three-quarters of that size. The rocks’ cumulative volume was 120 by 50 by 20 feet, and one of the rocks left a 2-foot-deep depression in the roadway that’s about 12-by-10-feet.
A similar-sized rock fall incident at the same location closed the highway for several days starting April 27, 2007, CDOT said. Sunday’s incident involved rock from higher up the slope. Geology consisting of sandstone on layers of shale contributes to the size of rock fall incidents in the area.
Crews began using pry bars to bring down threatening rocks, also employing air bags inflated behind rocks to break them free. Once the hillside is stable, crews will blast rock on the roadway and haul it away.
The detour route makes use of state highway routes 92 and 65; Interstate 70; and Colorado Highway 82. CDOT plans to post updates on the closure at http://www.cotrip.org.
Meanwhile, CDOT is continuing an ongoing rock scaling project north of the top of McClure Pass, between mile markers 44 and 49 near Marble. That work is requiring closures that sometimes will last 20 minutes or more, along with shorter delays and single-lane, alternating traffic during daylight hours Mondays through Fridays and some Saturdays.
Ty Ortiz, CDOT’s rockfall specialist, said McClure is ranked at the top of the agency’s Rockfall Hazard Rating System.