Life-Cycle Cost Minimization and Sensitivity Analysis for Mechanistic-Empirical Pavement Design

Abstract

Rebuilding and maintaining the nation’s highway infrastructure will require very large capital outlays for many years to come. While the expenditures involved in the maintenance and construction of highway facilities are large, current methods of pavement design used in common engineering practice do not routinely take advantage of design optimization methodologies. This paper presents an optimization formulation for mechanistic-empirical pavement design that minimizes life-cycle costs associated with the construction and maintenance of flexible pavements. Sensitivity analysis is performed on the model to understand how the optimal design changes with respect to variations in the critical design inputs. Using typical values for the costs associated with the construction of each pavement layer and the reconstruction of failed pavement sections, it is determined that extended-life flexible pavements may provide significant life-cycle cost savings despite their higher initial construction cost. However, perpetual pavements that control critical strains to levels near the fatigue and endurance limits for the hot mix asphalt (HMA) and subgrade soil should be designed only when traffic levels are sufficiently high to warrant them or when sufficient uncertainty exists in the mean values of design input probability distributions. Optimization studies performed under uncertainty have showed that designs for extended-life pavements are robust with respect to physical variability in material properties, but are significantly impacted by a lack of knowledge of probability distributions.