Crews to Reconstruct Damaged Crib Wall on US 550 Red Mountain Pass

Crews have been working on this US 550 crib wall since mid-July, after it was damaged by a severe storm event and flooding of mud, rock and debris. The reconstruction includes extending the structure by 20 feet, installation of new steel posts, installation of micro-piles, installation of a concrete wall for a more stable road surface and the final wood timber facing.

SOUTHWEST COLORADO—Crews are wrapping up emergency repair work to the damaged road and crib wall on US Highway 550 Red Mountain Pass, just south of Ouray.

Last week, the crew finished rebuilding the structural elements of the crib wall—a retaining structure that provides support and stabilization of the road surface. They are working this week on the non-structural (non-supportive) timber facing.

The team permanently fixed the structure in collaboration with CDOT's engineering and geo-technical units, and with contractor Geostabilization International's (GSI) design and construction work. While the team thought it could only compelte temporary repairs before embarking on a larger-scale project in the fall, they are scheduled to complete this work this week.

Once the road work is completed, GSI will bring in a separate crew to climb the Ruby Walls (the cliff face above the highway) to begin work on the repair of existing rock fence. The rock fence captures debris that falls from the cliff and slopes above the highway. The crew will also perform minor scaling operationsto remove loose rock material ,which may present a rock fall hazard on the highway.

The final stage of work will not start until September, when the crew returns to construct a second rock-netting system below the existing fence that was installed a few years ago. The supplemental netting will increase the capacity for debris that falls from above.

Travel Impacts

Once the road work is completed, the portable traffic signal will be removed. However, travelers will still encounter flagging personnel, with periodic traffic stops of at least 20 to 30 minutes to allow for the rock scaling work and road clean up.

From 8 a.m. to 6 p.m., Monday through Friday, travelers can expect intermittent closures, until the rock-scaling work is completed next week. Travelers are urged to drive with extreme caution and be alert to workers and heavy equipment in the area.

A view from across the canyon, shows the new concrete wall just completed last week on US 550 Red Mt. Pass. Behind the concrete are new steel posts and micro-piles creating a more stable road surface. Crews this week will cover the concrete wall with a wood timber facing.

Project Info

Immediately following a severe storm event on Sunday, July 8, CDOT’s engineering and geotechnical units determined damage caused by debris which clogged the inlet at the bottom of the rock canyon. The flooding of water, rocks and other debris ran on top of the highway, instead of through the inlet. Water and debris also flowed over and around the support crib wall causing damage to the wood beam timber facing and washed out a significant amount of fill. This also caused damage to the main road support.

GSI was contracted to do the emergency repairs only 3 days after the storm event. The contractor's crew has been working diligently at the site since Wednesday, July 11. The repairs included:

• extending the crib wall by 20 feet, to the south;
• installing three rows of horizontal grouted steel posts; and
• installing micro-piles, drilled vertically into bedrock at the footing or base of crib wall to further stabilize the roadway.