The project produced a mechanistic-empirical (M-E) pavement design guide that includes (a) a Guide for M-E design and analysis, (2) companion software with documentation and a user manual, and (3) implementation and training materials. The guide includes procedures for the analysis and design of new, rehabilitated flexible, rigid, and semi-rigid pavements. It uses M-E numerical models to analyze input data for traffic, climate, materials, and structure to estimate damage accumulation and predict performance, in terms of distress and smoothness, over service life for comparison with threshold values (i.e., it does not provide structural thickness as an output).

AASHTO's Guide for the Design of Pavement Structures is the primary document used to design new and rehabilitated highway pavements. It was based on empirical design approaches derived from the AASHO Road Test that included limited structural sections at one location, and with limited traffic levels compared with those of the present day. Because mechanistic approaches more realistically characterize in-service pavements and improve the reliability of designs, design approaches that are based on mechanistic principles would be desired. However, because of gaps that exist in the knowledge base, mechanistic design methods need to be supported by empirical relationships, and many of the issues relating to the M-E approach need to be better defined before practical and realistic design procedures can be developed and put into use. Thus, there was a need to address related issues and develop a Guide for Design of New and Rehabilitated Pavement Structures, based on M-E principles, accompanied by the necessary computational software, for adoption and distribution by AASHTO.

The research reviewed relevant domestic and foreign literature, research findings, current practices, and databases relative to pavement analysis and design; developed a design guide based on sound mechanistic principles; presented the Guide as a computational software; and provided related documentation and training materials. The Guide provides a uniform basis for the design of flexible, rigid, and composite pavements and employs common design parameters for traffic, subgrade, and environment. It uses M-E performance models that were calibrated using field data from the Long Term Pavement Performance studies and other sources.

The Mechanistic-Empirical Pavement Design Guide, its related documentation, and companion software developed in this project are available on-line at http://www.trb.org/mepdg/ (The Pavement Design Guide is provided in an Adobe PDF format that is read-only and cannot be saved, printed, or edited. The software can be downloaded for installation on a local drive in executable form, but its copy-protection feature requires access to the Internet to check for a specific file on a web server of the Transportation Research Board at each use). Also, copies of the Guide and software and related documentation have been distributed to NCHRP sponsors (i.e., the state departments of transportation) and the members of the AASHTO Joint Task Force on Pavements. Follow up activities to facilitate use and implementation of the Guide are being performed under NCHRP Project 1-40.