The effect of axle load spectra from AASHTO method on flexible pavement performance

Abstract

 

 Currently, methods used for pavement design are empirical and based on experiments conducted in the 1960s. Due to the number of variables that can influence an empirical analysis, the National Cooperative Highway Research Program (NCHRP) proposed a mechanistic-empirical method. Based on this method, the MEPDG (Mechanistic-Empirical Pavement Design Guide) software was developed and later, its improved version, the AASHTO Ware Pavement ME Design. In both software versions, default values were developed from traffic data of the United States. However, characteristics of the Brazilian traffic are different from characteristics in the United States. Therefore, this study aimed to verify the effect on national pavement performance due to the use of the default axle load spectra that are available on both software versions. Thus, computer simulations were performed using Brazilian axle load spectra, based on data collected at the Imigrantes Highway in São Paulo, and using the default load spectra of the software. The results show that the Brazilian axle load spectra studied damages more the national pavement than the default spectra of the software. Therefore, it is not recommended the use of default spectra for designing Brazilian highways similar to the one studied, because this would lead to under-designed structures.