Redi-Rock Walls Support Winding Mountain Bridge

Project Name

Big Cottonwood Canyon Loop Road Bridge #94

Customer Name
Tavaci, Inc.

Design / Specifying Engineer
Stantec Consulting and IGES

Block Manufacturer
Castle Rock Precast

Wall Installer
Harper Construction

Project Location
Salt Lake City, Utah

Year Built

Project Scope

With mountain views and access to some of the best skiing in the west, this upscale development outside of Salt Lake City, Utah required an impressive and inviting entrance; however, access to the canyon was restricted by steep terrain and a wildlife easement.

The Tavaci development is anything but conventional, and the Tavaci entrance follows suit. Instead of excavating the slope and cutting a path for a switchback roadway up the canyon, designers specified a cast-in-place concrete, box girder bridge according to an article published in the Fall 2008 issue of ASPIRE magazine. The bridge includes five spans and a "severe horseshoe bend."

In order to provide adequate support, "substantial cheekwalls and finwalls at the abutments" were required.

The owners of Tavaci chose the Redi-Rock retaining wall system due to Redi-Rock's ability to build tall gravity walls without the need for geogrid tie backs. Redi-Rock requires minimal excavation behind walls, whereas reinforced walls require extensive excavation to provide room to place geogrid. The texture and ability to be colored were also strong selling points for the Redi-Rock system.

Tavaci designers did not want massive, imposing walls so they designed the walls with a terraced look. Near the entrance to the development, several tiers of Redi-Rock 28 in. series blocks compose six-feet-tall gravity walls that provide erosion control and structural support. The walls abutting the bridge stand 12-14 ft. high and are reinforced with geogrid.

Installing the walls was so simple that the General Contractor, Harper Construction, took over installing the walls soon after block manufacturer Castle Rock Precast demonstrated the process.

After the first Redi-Rock walls were installed, the owners decided to move the bridge and roadway to better accommodate construction. Because Redi-Rock is a segmental retaining wall system, crews were able to remove the blocks and re-build the wall—a task that could not have been accomplished with a poured-in-place wall.

Castle Rock Precast worked with the engineers to provide a design to anchor the guard rails behind the walls.

The developer wanted to stain the bridge to match the hues of the surrounding canyon. Designers chose Permeon, an environmentally friendly "desert varnish" to stain the bridge, curbs and retaining walls, tying the entire project together.

The bridge was awarded the 2008 Portland Cement Association Bridge Award.

Design Manual

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