Intermittent Closures of US 550/ Red Mountain Pass for Rock Scaling This Next Week

04/28/14 | By More

OURAY COUNTY – The Colorado Department of Transportation announced earlier this week that it is planning more road closures of Highway 550/Red Mountain Pass beginning next week, to conduct rock scaling near mile marker 90 south of Ouray, in an area where there was a massive rockslide last winter.

Although plans are not completely firmed up yet, CDOT spokeswoman Nancy Shanks said that the highway will likely be closed to through-traffic between Ouray and Silverton from 8:30 a.m.-12:30 p.m. and 1:30-6 p.m. Monday through Saturday for two to three weeks, starting next Monday, April 28.

During hours when the closures are not in effect there will be signal-controlled alternating one-way traffic, as has been the case since last February.

CDOT has initiated emergency contracting procedures to bypass a bidding process that would otherwise take weeks, to allow the rock scaling project to mobilize immediately.

“We need to start clearing the slope now that things are loosening up with warmer weather,” Shanks explained.

Scaling will be done by hand, using pry bars to bring down rocks perched on the steeply angled slope of the Ruby Walls, hundreds of feet above the highway.

Last winter, as part of the initial mitigation effort following the rockslide, CDOT contractors installed metal mesh over much of the area where the rocks remained perched, in an effort to prevent further rockfall; they also installed a rockfall fence alongside the highway to protect motorists as they drive past the area.

The fence is doing its job, Shanks said, “but rocks are still coming down and sometimes they get through the fence, which is there to slow them.”

The upcoming rock-scaling project does not represent a permanent fix to the rockfall problem in the area. “We will come back again in the summer to do the larger mitigation project we had always talked about, placing more mesh on the slope, and possibly closer to the roadway,” Shanks said.

The ordeal began on Sunday evening, Jan. 12 when it began “raining rocks” at mile marker 90 on US 550/ Red Mountain Pass. Crews cleared the highway and reopened it to travel that night, but when a steady stream of rubble continued to pour down on the roadway the next day, CDOT officials decided to close the highway again. It would remain fully closed for the next two-and-a-half weeks – the longest closure due to rockfall that anyone can remember. 

CDOT geologists discovered that the slide had initiated from a near-vertical rock slope 900 feet above mile marker 90, when a slab of rock the size of a football field broke free from the surrounding rock and fractured into smaller pieces of rock rubble. After the initial release, thousands of tons of material remained perched on the cliff face, endangering motorists below.  

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