Stabilizing Colorado’s Highway 119 with Redi-Rock Gravity Walls

Project Name: Colorado State Highway 119 Owner: CDOT (Colorado Department of Transportation) Contractor: Miller Wall Company Engineer: Ground Engineering Manufacturer: Signature Stone Location: Boulder County, CO Wall Type: Gravity Wall Texture: Ledgestone Year Built: 2022 Wall Area: 11,857 sq ft (1101.5 sq m)

I'm Sam Carter with Miller Wall Company. I'm the general manager. Been with the company for about ten years and built Redi-Rock Walls all across Colorado, Wyoming. Done a number of projects successfully from the CDOT Bail Chain Station in I seventy, done Microsoft data centers in Cheyenne, Wyoming, as well as industrial, residential, and commercial projects in Denver. We're standing here on Colorado State Highway one nineteen in Boulder Canyon in Colorado. We're at the intersection of Sugarloaf Road and State Highway one nineteen. This is a three tiered Redi-Rock wall system that was partially funded by FEMA due to flood relief that had damaged old natural boulder walls and bin block walls that were retaining Sugarloaf Road, and they experienced major settlement events. On this project specifically, there are three wall tiers and the maximum height is about forty five feet of total retained grade separation. We use all manner of Redi-Rock blocks, XL blocks of all sizes, as well as interesting things like combining flow fill, as well as course aggregate backfill, working with the bedrock tie ins, and complicated engineering requirements. As you can see, we're on a very steep slope here in this canyon, and space is limited while still needing to maintain an open lane of traffic during construction. We had to squeeze an enormous amount of grade separation into a tight space while still thinking about slope safety and wall long term stability. Ground engineering was our partner on this, and when site conditions varied from planned elevations to field conditions, we were able to provide value engineering solutions to the client that delivered the project on time and on budget, while solving a really cool problem. Redi-Rock is the obvious choice for a wall solution like this. When you're dealing with the space constraints, many of these blocks were set by a crane or set by a machine that was set by a crane, crane, and you can't do that with any other wall system, small block, or cast in place concrete, where Redi-Rock just is a set and go structural solution. It's a obvious choice for a project like this.

When failing walls put Colorado’s Highway 119 at risk, Ground Engineering and Miller Wall Company stepped up to solve the challenge with an adaptable 3-tier Redi-Rock gravity wall system. Watch the video and explore the case study for the whole story.

image of walls being installed for road

THE CHALLENGE

Replacing a compromised boulder and bin block wall on Colorado State Highway 119’s Sugarloaf Road needed adaptable engineering. The failing walls had experienced significant settlement, putting the stability of the roadway at risk. Adding to the complexity, the project site sat on a steep canyon slope with limited space for construction, while still needing to maintain at least one open lane of traffic. With major engineering and logistical challenges from the start, the project team needed a reliable, space-efficient solution—and that’s where Redi-Rock came in.

THE SOLUTION

Ground Engineering and Miller Wall Company teamed up to design a CDOT (Colorado Department of Transportation) approved three-tiered gravity Redi-Rock retaining wall system. Using the 72 in (1830 mm) and 52 in (1320 mm) XL blocks, 60 in (1520 mm), 41 in (1030 mm), and 28 in (710 mm), and with the selection of the Ledgestone Texture, the wall design was prepared and turned over to Signature Stone to manufacture the required Redi-Rock blocks.

image of redi-rock walls for highway

THE DESIGN

This project required creative and adaptive wall engineering to overcome difficult site conditions. Here's how the team delivered a safe, stable solution with tight design constraints:

Multi-Tiered Wall System: Three distinct tiers of Redi-Rock walls were constructed with a total retained grade separation of 45 ft (13.7 m)
Utilization of The Redi-Rock Block Library: A wide variety of blocks allowed maximum design flexibility on a steep, confined site.
Specialized Backfill Solutions: To remedy bedrock conditions, the combined use of flowable fill, recycled concrete, and class one structural fill was implemented.
Adaptive Design: The original plan was to cut a ½:1 slope into bedrock and backfill with flowable fill. However, the bedrock elevations varied significantly, calling for a revised approach that required bedrock tie-ins.
Geotechnical Teamwork: Miller Wall Company partnered with Ground Engineering to value engineer solutions that maintained budget and schedule.

“We used all manner of Redi-Rock blocks, XL blocks of all sizes, as well as interesting things like combining flow fill, as well as course aggregate backfill, working with the bedrock tie-ins, and complicated engineering requirements.”

-Sam Carter, Miller Wall Company

close up of redi-rock wall next to road

THE INSTALLATION

Tight spaces and steep slopes made installation challenging, but Miller Wall Company and Redi-Rock made it possible to safely navigate the construction site with:

Crane-Set Precision: Many of the blocks were installed using a crane.
Modular Design: Redi-Rock’s large block system enables setting and going without complex formwork or staging.
Unmatched Efficiency: With a machine-set installation, Redi-Rock kept crews working efficiently in even the most constrained conditions.

With the above efficiencies in place, one traffic lane remained open throughout the installation, despite limited workspaces. The flexible installation methods and real-time design adjustments ensured the project stayed on schedule and within budget.

image of redi-rock walls between highway roads

THE OUTCOME

Completed in 2022, the project delivered 11,857 sq ft (1101.5 sq m) of durable, engineered Redi-Rock retaining walls, replacing the instability of the former boulder and bin block walls with a long-term, engineered solution. The Ledgestone finish gives the project the natural stone look needed to blend with the mountain landscape, fusing beauty and durability to keep the roadway stable and travelers safe.

Explore Redi-Rock retaining wall engineering resources, or continue reading about projects where Redi-Rock wins in the Knowledge Hub.

“Redi-Rock is a set-and-go structural solution.”

-Sam Carter, Miller Wall Company

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72 in (1830 mm) XL Hollow Core 52 in (1320 mm) XL Hollow Core 60 in (1520 mm) 41 in (1030 mm) 28 in (710 mm) 90 Degree Corner Block

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