Case Study
Interstate Highway 40, Oklahoma, United States
Introduction
Between 1997 and 2012, Oklahoma’s GDP grew by 45 percent from $110 billion to $160 billion. While a diverse range of industries – including aviation, energy and food processing – fueled the state’s growth, the roadway system made it possible by carrying more heavy traffic each year.
Challenge
The increasing traffic, along with poor soil, caused many of the roadways to rut excessively. One particularly troublesome problem was a two-mile section of Interstate 40 west of Oklahoma City. Due to the excellent performance of their HiMA rehabilitation project at the National Center for Asphalt Technology, the Oklahoma Department of Transportation (ODOT) decided to address the rutting problem by using HiMA technology.
Resolution
The ODOT designed a thin perpetual pavement solution using HiMA for the I-40 section in Caddo County. The solution consisted of 3.8 cm (1.5 in) of the HIMA fatigue-resistant rich bottom layer, followed by 6.4 cm (2.5 in) of OK S3 HiMA dense-graded mixture, 3.8 cm (1.5 in) of OK S5 HiMA dense-graded mixture and finished with 1.9 cm (3/4 in) of the open-graded friction course.
Lion Oil produced and delivered the HiMA binder, which the ODOT specified as PG76-28E. Haskell Lemon Construction Co. was awarded the project as the general contractor. The asphalt mixtures were produced at 163°C (325°F). Since the new pavement was thinner than the conventional new construction, no guard rail or grade adjustments were necessary. The contractor reported that HiMA mixtures handled similarly to conventional PMB.
After seven years in place, supporting an additional 33 billion GPD growth and over 17 million equivalent single axle loads (ESAL), there has been no rutting issues or patching. The section maintained the Pavement Quality Index of 96 and 94 out of 100.