Recommended Changes to Designs Not Meeting Criteria Using the Mechanistic-Empirical Pavement Design Guide.

The newly Mechanistic-Empirical Pavement Design Guide (MEPDG) allows engineers to design pavement structural layers to sustain predefined limits of distress levels due to traffic loads and environmental conditions based on nationally/locally calibrated performance models. Users are required to input variables related to traffic, environment, and materials. In addition, reliability and limiting values of the distresses are required inputs. MEPDG in its current version is an analysis procedure rather than a design tool. However, it is intended to be also used as a design tool. Thus, the design process of the pavement structure in MEPDG is a trial process. It starts with assuming a structure and material properties and then performing the analysis. If the proposed trail did not meet the criteria, then the material properties and/or layer(s) thicknesses are changed until the design meets the criteria. This paper presents a reference document to assist pavement designers in identifying the most important MEPDG key inputs to modify such that the predicted distresses meet predefined design criteria. Results showed that, pavement structural design should be coupled with the mix design and selection of material properties in order to achieve an economic design complying with the criteria. [ABSTRACT FROM AUTHOR]