Strategies for Life-Cycle Cost Analysis Based on Mechanistic-Empirical Performance Prediction for Asphalt Pavements Designed by Different Approaches

Increasing traffic loads require specific pavement design considerations to guarantee proper performance and adequate life cycle. The traditional empirical design method based on the AASHO Road Test has been established in Brazil since the 1960s. A newly proposed mechanistic-empirical design method is under implementation and considers pavement deterioration in terms of fatigue cracking and permanent deformation. In this chapter, the prediction of cracked area is used as the parameter to estimate maintenance cycles. With the definition of the analysis period in a roadway project, which accounts for construction and maintenance activities, costs can be computed. The objective is to evaluate the direct costs during the life of pavement structures designed by different approaches: empirical and mechanistic-empirical, considering different traffic levels. The maintenance criterion was established as a maximum allowed predicted cracked area of the surface layer. The maintenance activity consisted of milling the surface layer, followed by its complete reconstruction with the same material. The results indicate that the pavement designed by the empirical method led to lower thickness of the surface layer while requiring more maintenance cycles, which resulted in higher overall values of direct costs. The structure designed by the mechanistic-empirical method presented better performance, with a more attractive overall cost, despite higher construction costs. For very high traffic levels, the study indicates that there may be cost savings when designing the asphalt pavement by the mechanistic-empirical approach because there is a need for less maintenance cycles.