The Michigan Department of Transportation (MDOT) is in the process of changing its design procedures for flexible pavements and overlays from one based on the AASHTO Guide to a mechanistic approach. Two computer programs, MICHPAVE, for flexible pavement design, and MICHBACK, for back-calculation of pavement layer moduli from FWD deflection data, are intended to be the cornerstones of MDOT’s mechanistic design procedure. MICHPAVE has linear and non-linear finite-element pavement models to predict the primary pavement responses, and field-derived fatigue and rut models to predict the secondary response. There is a need to verify/calibrate the distress models in MICHPAVE using field observations and the distress data bank in the MDOT Pavement Management System (PMS). In addition, MICHBACK currently does not include an overlay design procedure. Adding this capability to MICHBACK is also critical to the success of a mechanistic pavement design procedure.

The project objectives are: (1) to verify/calibrate the rut and fatigue distress models in MICHPAVE using field data from a spectrum of in-service flexible and composite pavements in the state of Michigan and develop alternate models or improve existing models if necessary, (2) develop a mechanistic based flexible overlay design procedure in MICHBACK based on non-destructive deflection test data, to be implemented in MICHBACK as part of the companion project, and (3) the revised MICHPAVE design program will output pavement cross-sections (balanced) that satisfy fatigue, rut, and ride quality thresholds.