THE CHALLENGE
In 2015, the Kentucky Transportation Cabinet (KYTC) began work on the multi-million-dollar New Circle Road widening project in Lexington. The scope of the project included nearly 3.2 miles of lane additions, shoulder widening, on-ramp and exit ramp realignment, and bridge widening between Hwy. 60 (Versailles Road) and Hwy. 421.
To make the highway improvements possible, eight drilled pier soldier pile cantilever retaining walls were specified to accommodate grade changes throughout the project. After the contract for the job was awarded to ATS Construction, estimator and project manager Amos Hubbard began searching for a more cost-effective and efficient alternative for the walls on the project. “We proposed changing to gravity retaining walls. The state asked if we would consider using Redi-Rock, and we said we would love to,” said Hubbard.
THE SOLUTION
Redi-Rock is a complete, engineered retaining wall system that uses massive, precast concrete blocks that stack together like giant Lego blocks to build walls that stand the test of time. Redi-Rock gravity blocks are used to build tall retaining walls without the need for geogrid reinforcement.
Clint Hines, P.E., consulting engineer at JC Hines & Associates, was brought in to determine if Redi-Rock could be used to value engineer the walls on the New Circle Road project.
Hines explained, “The close proximity of competent limestone bedrock to the proposed bottom of wall elevation for most of the walls on the project gave us some great options for proposing optimized modular gravity wall structures. By taking advantage of the ability to key into the rock and an occasional base course of deeper setback Redi-Rock block units, we were able to make a maximum overall design height of 18 ft work within the limits of AASHTO LRFD design requirements.”
With Hines’ help, the value engineered proposal using the Redi-Rock gravity retaining wall system met AASHTO/LRFD specifications and was accepted by the KYTC.
Central Bridge Company and Redi-Rock of Kentuckiana, the local Redi-Rock manufacturer and installer, were challenged with strict deadlines as they began constructing the walls, which were part of the first two phases of New Circle Road project. Both phases needed to be completed prior to the 2015 Breeders Cup being held at the Keenland race course in late October, or Central Bridge would face a $100,000 per day penalty.
Additionally, construction could not impede the flow of traffic along the highway, which was especially difficult along the stretch of highway adjacent to Calumet Farms where the easement was limited. Fortunately, the Redi-Rock gravity system is designed to install quickly and within a small footprint using a few pieces of machinery and a small crew. In fact, installation of all eight retaining walls was completed in just 38 working days.
THE OUTCOME
Prior to completion, a ninth ramp wall was added to the project, bringing the total wall area to 41,000 sq ft. Over 7,200 Redi-Rock blocks in the Ledgestone face texture were used on the project.
In all, the value-engineered design of the New Circle Road project using Redi-Rock saved the state and ATS Construction $478,445, as well as several weeks' worth of construction time.
Find out how Redi-Rock can help on your next roadway project at redi-rock.com/roads.
