Evaluation of the Mechanistic–Empirical Pavement Design Guide model for permanent deformations in asphalt concrete

The model for permanent deformation in asphalt concrete (AC) layers used in the Mechanistic–Empirical Pavement Design Guide (MEPDG) was evaluated. Two instrumented flexible pavements were subjected to heavy vehicle simulator testing at three constant temperatures. Permanent deformation modelling was carried out using the MEPDG software v1.003 at the highest accuracy level. The nationally calibrated model resulted in underprediction by 35–45%. Model results were successfully calibrated to fit observation using field calibration factors that increased temperature susceptibility by 45–50% and decreased the dependency of the number of loadings by 30–40%. The field calibration factors should be confirmed by studying existing pavements before being employed. The model did not assess the permanent deformation contribution of each AC layer correctly. Therefore, the model should be refined with further trench studies using in-service pavements.