Calibration and Implementation of Flexible Pavement Portion of Mechanistic-Empirical Pavement Design Guide for Washington State Department of Transportation.

The Mechanistic-Empirical Pavement Design Guide (MEPDG) is proposed as anadvanced pavement design tool which integrates up-to-date pavement practices. Since the release of the MEPDG in 2004, the Washington State Department of Transportation (WSDOT) has been continuously working on calibration and evaluating the program with regard to implementation for state and local agencies. This paper presents WSDOT’s latest efforts on the calibrationof the flexible pavement portion of the MEPDG against the data obtained from the Washington State Pavement Management System (WSPMS). It first describes the preparation process of the required input data. Detailed descriptions of input values are provided, since they may be generally applicableto states with similar conditions. The calibration process is described and followed by a discussion of results and potential implications. Emphasis is placed on major observations and general issues encountered in the calibration process. An implementation plan is being prepared to potentiallyreplace the current AASHTO 1993 Design Guide with the MEPDG in WashingtonState. This study provides valuable conclusions for national applications: (1) the flexible pavement distress models were calibrated successfully; (2) WSDOT flexible pavements require local calibration differently from the defaults; and (3) A software bug does not allow calibration of the roughness model. Results indicate that, with a few improvements and resolving software bugs, MEPDG software can be used as an advanced tool to design flexible pavements and predict future pavement performance.