BACKGROUND: The AASHTO interim edition of the Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) and related software developed under NCHRP provides methodologies for the analysis and performance prediction of different types of flexible and rigid pavements. The performance predicted by these methodologies (in terms of distresses such as cracking, rutting, faulting, and smoothness) for the anticipated climatic and traffic conditions depends on the values of input parameters that characterize pavement materials, layers, design features, and condition. However, these input parameter values are expected to differ to varying degrees and, therefore, the predicted performance may also vary to some degree depending on the input parameter values. Although studies have been conducted to relate predicted performance to differences in input parameter values, these studies have not addressed this relationship in a systematic manner to identify the relative influence of input parameter values on predicted performance. Also, these studies have not considered the combined effects of variations in two or more input parameter values on predicted performance in a comprehensive manner.
Research is needed to determine the degree of sensitivity of the performance predicted by the MEPDG to input parameter values. This information will help identify, for specific climatic region and traffic conditions, the input parameters that appear to substantially influence predicted performance. In this manner, users can focus efforts on those input parameters that will greatly influence the pavement design.
OBJECTIVE: The objective of this research was to determine the sensitivity of the performance predicted by the MEPDG to variability of input parameter values. The research dealt with all types of flexible and rigid pavements included in the MEPDG and was conducted using the MEPDG software version available as of October 1, 2008.
Status: The project is complete. The contractor's final report is available at