Critical Assessment of the Long-Term Performance and Cost-Effectiveness of a New Pavement Preservation Method: Micromilling and Thin Overlay

Abstract

The Georgia Department of Transportation (DOT) has developed and implemented a new pavement preservation method that uses micromilling in conjunction with a thin overlay for cost-effective replacement of a deteriorated, thin, open-graded surface layer (¾ to 1¼ in.) without removing the sound underlying layer. The new method was first implemented in 2007 on a 15.3 mi section on I-75 near Perry, Georgia, and resulted in significant savings. In considering whether to adopt the new method as standard practice in pavement preservation, it is essential to evaluate the method’s actual, long-term performance. This is the first paper to report the actual, long-term performance of the new method. The study used 8 years of pavement condition data collected by the Georgia DOT and sensing data collected by Georgia Institute of Technology. Based on the data, the pavement on I-75 is still in good condition after 8 years (with 6% raveling in 2015). Based on the current condition and the Georgia DOT’s past experience with open-graded surface mixes, the Georgia DOT anticipates an additional 2 to 3 years of service for the I-75 project. This provides a service interval of 10 to 11 years, which is comparable to that of Georgia’s conventional pavement rehabilitative strategy for open-graded surfaced Interstate pavements, which typically ranges from 10 to 12 years. The equivalent uniform annual cost of the new method is $11,200 per lane-mile per year, which is 11% lower than the $12,600 per lane-mile for the conventional rehabilitation method computed on a 12-year service interval. This information can assist transportation agencies in making decisions about whether to apply the new pavement preservation treatment.