There are several accepted flexible-pavement design procedures available, including the Asphalt Institute method, the National Stone Association procedure, the Shell procedure, and the Mechanistic-Empirical Pavement Design Guide (which is briefly discussed later in this chapter). Most of the procedures have been field verified and used by highway agencies for many years and the selection of one procedure over another is usually based on highway-agency experience and satisfaction with previous design results.
A traditional and widely accepted flexible-pavement design procedure is presented in the AASHTO Guide for Design of Pavement Structures, which is published by the American Association of State Highway and Transportation Officials (AASHTO). The procedure was first published in 1972, with the latest revisions in 1993. Test data, used for the development of the design procedure, were collected at the AASHO Road Test in Illinois from 1958 to 1960 (AASHO, which stands for American Association of State Highway Officials, was the prior name of AASHTO).