In 2004, NCHRP 1-37A was completed and delivered a mechanistic-empirical pavement design guide and accompanying software.
In 1996, to achieve a state-of-the-practice pavement design procedure, the AASHTO Joint Task Force on Pavements sponsored the development of a mechanistic-empirical design guide for new and rehabilitated pavements, through the National Cooperative Highway Research Program (NCHRP). The AASHO Road Test was conducted from 1958 to 1960 using limited pavement sections and modest traffic levels as compared to those used today. The basis of this design has been the empirical equations developed from the AASHO Road Test. The 1993 AASHTO Guide for the Design of Pavement Structures (and previous versions) is one of the primary documents used by state highway agencies for designing new and rehabilitated pavements.
