TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 308: Changes to the Mechanistic Empirical Pavement Design Guide Software Through Version 0.900, July 2006, summarizes numerous changes made to the original Version 0.7 of the Mechanistic-Empirical Pavement Design Guide (MEPDG) software. Specifically, the digest describes the corrections incorporated in Version 0.8 (released in November 2005) and the mainly technical improvements and enhancements included in Version 0.900 (released in July 2006).