Fast construction in tight space keeps Wash. highway open

Case Studies
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Traffic disruptions were a major concern when Walla Walla County in Washington launched a recent highway-widening project.


On one side, this busy stretch of Old Milton Highway was hemmed in by a private residence. On the other side, an access road ran parallel to the highway but nearly 30 ft above.


“The road was 20 ft wide and we needed to widen it to about 40 ft, which meant cutting back into the hill about 20 ft,” explained David Eids, chief of Engineering & Construction for the Walla Walla County Department of Public Works.


Cutting back the slope required a 500-ft-long retaining wall that would stand 16.5 ft tall at its highest point. “We looked at various different types of walls, and almost all of them would have an impact on the road; we’d have to move the road and buy additional right-of-way,” Eids explained.


The site consisted of a loess soil (sandy silt in this case). To achieve 16.5 ft in the highest portion of the wall, the wall was designed using five courses of Redi-Rock 60-in. base blocks at the base of the wall, five courses of 41-in. blocks, and one course or 28-in. blocks. 


“Other alternatives considered would have required additional excavation and impacted the access road,” Eids said.


An additional benefit was the aesthetics the system offered. The blocks are available in three natural stone textures, but the county felt the newest, most natural texture—Ledgestone—would be the best fit for the project. “Although rural, this area borders an urban area with numerous wineries,” Eids explained. “It was felt that the Ledgestone finish could decrease the possibility of graffiti and the colored natural-rock-type finish would blend in with the surrounding terrain.”


In total, 6,000 sq ft of Redi-Rock blocks were installed in just 3.5 weeks.


“It’s a really great-looking job,” explained Rick Woodard, who owns the home directly across the road from the new wall. “I had a real-estate guy come out, and it’s increased my property value. It made the area look a lot better.”


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