Project Summary
In Cold Lake, Alberta, a project site experienced extremely heavy industrial traffic, with 1,200 to 1,500 40-kip axle loads daily. The owner initially applied a 4-inch (10 cm) lift of cold mix over a prepared subgrade to address a persistent maintenance challenge. The cold mix was intended to reduce dust and limit grader maintenance. However, the frequent traffic and heavy loads quickly overwhelmed the structure, causing it to fail within a year.
solution
The owner reached out to Layfield to explore using the GEOWEB® Geocell System to upgrade their unpaved roadway. They sought a solution to enhance the subgrade modulus of the cold mix sections on their access roads. The ACP had historically underperformed due to weak subgrade and heavy loads. Leveraging the owner’s prior experience with GEOWEB® Load Support System for unpaved roads, we collaborated with Presto Geosystems to create a design cross-section and deployment plan. This approach aimed to meet traffic demands, reduce maintenance, and improve the roadway’s overall performance.
installation
An assessment was completed on the current roadway’s structural number (SN), and its capacity to handle traffic loads was calculated. The existing design, built for 780,000 ESALs, was far under-designed for the support it needed. This mismatch caused rapid deterioration, especially during spring, with the road failing within a year. Standard calculations showed that the roadway required a capacity of 5.3 million ESALs to meet traffic demands.
As the roadway was a critical access route, full closure wasn’t an option; a phased plan to refurbish half of the road at a time was developed. During the day, traffic flow was maintained with flag-controlled diversions, and at night, the section was reopened to avoid 24-hour flagging.
The upgraded design included an enhanced woven geotextile over a prepared subgrade with a CBR of at least 3%, followed by GEOWEB® Cellular Confinement (GW30V6), filled with compacted granular material and overfilled by 4 inches. A 4-inch cold mix Asphalt Concrete Pavement (ACP) layer completed the section, resulting in a durable structure of 250 mm granular base and 100 mm cold mix ACP.
results
Over 14 km of roadway has been successfully installed, leveraging AASHTO 93 design calculations and the GEOWEB® System to improve the granular material’s load-carrying ratio (LCR) from 0.15 to 0.34. This allowed the section thickness to be reduced from 450 mm to 250 mm while meeting ESAL requirements. The GEOWEB® System also stabilized the gravel layer above it, minimizing frost heaves, rutting, and differential settlement. After years of service, the roadway remains exceptionally durable with reduced maintenance needs.
