Comparative Analysis of Input Traffic Data and MEPDG Output for Flexible Pavements in State of Arizona

This paper is concerned with the effects of input traffic parameters on the pavement performance predicted by the Mechanical Empirical Pavement Design Guide (MEPDG) for the state of Arizona. This study examined the differences in input traffic data from different sources and their impact on the pavement distresses at the end of a design year. Moreover, the national default load distribution factors were compared with the site-specific distribution factors measured as part of the Long Term Pavement Performance (LTPP) program by evaluating the errors associated with predicting various pavement distresses. Findings showed that average daily truck traffic (ADTT) varied significantly between two data sources (LTPP and Arizona Department of Transportation), resulting in large differences in predicted longitudinal and alligator cracking. A further sensitivity analysis revealed that the longitudinal and alligator cracking increased by a larger factor with respect to increases in ADTT. The use of national default load distribution factors revealed a similar result, such that the errors associated with predicting cracking were large.