Effects of overlay designs on reliability of flexible pavements

Management of flexible pavements requires timely application of preventive maintenance and rehabilitation actions such as overlays. These actions are an integral part of a design strategy that minimises the use of recourses over the pavement's life-cycle. The objective of this paper is to develop a reliability model for flexible pavements that accounts for the effects of overlay designs. In this paper, the pavement responses are determined by the linear theory of elasticity for the system of pavement layers, while the pavement reliability is represented as a series system of two failure criteria: fatigue cracking and rutting. To illustrate the developed model, a numerical study is presented. Sensitivity and importance measures are computed for the parameters and the random variables included in the limit state functions. The sensitivity measures suggest that the initial asphalt layer thickness and the sub-grade stiffness are the critical predictors of the pavement performance after application of a structural overlay.