Preliminary Local Calibration of Performance Prediction Models in AASHTOWare Pavement ME Design for Flexible Pavement Rehabilitation in Oregon

Abstract

The Oregon Department of Transportation (ODOT) is in the process of implementing the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for new pavement sections. However, the vast majority of pavement work conducted by ODOT involves rehabilitation of existing pavements. Hot mix asphalt (HMA) overlays are the preferred rehabilitation treatment for both flexible and rigid pavements in Oregon. HMA overlays are also susceptible to fatigue cracking (alligator cracking and longitudinal cracking), rutting, and thermal cracking just like what occurs in new HMA sections. Thirty-eight sections were used to calibrate the performance models for rehabilitation of existing pavement structures. A detailed comparison of predictive and measured distresses was made using the MEPDG released software AASHTOWare Pavement ME Design 2.0.19. It was found that AASHTOWare Pavement ME Design predictive distresses did not accurately reflect measured distresses, facilitating the need for local calibration of performance prediction models. Four distress prediction models (rutting, alligator cracking, longitudinal cracking, and thermal cracking) of the HMA overlays were calibrated for Oregon conditions. For checking the calibrations, comparisons were made between, before, and after calibrated results. While the thermal cracking model could not be calibrated, the locally calibrated models of rutting, alligator cracking, and longitudinal cracking provided better predictions with lower bias and standard error than the nationally (default) calibrated models.