Illinois Department of Transportation officials needed to erect sound-abatement walls along the Route 5 highway near Moline, Ill., as part of its widening and reconstruction project. But the terrain was rolling, requiring a flexible system that could follow the variations. They also wanted an attractive but cost-effective appearance.
Multi-colored precast concrete wall panels were specified, comprising 28 ground-mounted panels and 172 structure-mounted panels. A multi-colored painting system was used to create a cut-stone appearance. Utility Concrete fabricated the precast components, which were erected by McCarthy Improvement Co.
The structure-mounted panels span two steel beams anchored into the retaining wall below the panels through threaded rods. They connect to the columns’ base plates. The ground-mounted also connect to steel beams embedded into cast-in-place concrete piers.
“Precast concrete was specified due to the long-term performance and appearance it could provide,” says Duane O’Laughlin, transportation group manager at Ciorba Group, the engineer of record on the project. “We typically specify precast concrete for noise-abatement walls, as they typically perform better and are cost-effective compared to other systems.”
A ¾-inch-reveal, ashlar-stone texture with a 12-inch-wide smooth coping was created, with a multi-color paint system replicating the look of true stone designs. “IDOT District 2 specified this pattern, which has been used on other projects in the district,” O’Laughlin explains. “It fit with the character of the surrounding area best.”
The panels have a structural thickness of 4 inches, with the exception of a number of ground-mounted portions with a structural thickness of 8 inches because they retain some earth, according to Rudy Vidinhouede, Utility’s project manager. The heaviest structure-mounted panels are 10 feet tall and 14’-10” wide and weigh about 8,740 pounds. The heaviest ground-mounted panels are 10 feet tall and 20’-4” wide and weigh about 21,805 pounds.
The engineer worked with the precast concrete producer to create the most efficient design for the panels. “Due to portions of the walls being on retaining walls and other portions being ground-mounted, we gave close consideration to the sizing of the panels for constructability and erection purposes.”
The project was cast and erected without issues, creating an attractive, functional, and cost-efficient project. “We were very pleased with the results,” O’Laughlin says.