Development of a simple asphalt concrete overlay design scheme based on mechanistic–empirical approach

This study proposes a simple regression model for asphalt concrete (AC) overlay thickness design to be used in urban roads of Seoul city. A synthetic database for AC thickness design was generated using the Mechanistic–empirical pavement design guide. Multiple regression analysis was conducted to develop the AC overlay design model, which is a function of the total AC thickness, thickness ratio of AC overlay and existing layer, modulus ratio of old and new AC, subgrade condition, and traffic volume. The regression model was verified by comparing the predicted and measured annual average daily truck traffic (AADTT) and AC overlay thickness. It was found that the regression model has a correlation coefficient of .97 in determining AADTT. It was further validated using actual field performance data in which it has a correlation coefficient of .83 for AADTT prediction. It is observed from the validation study that the regression model is capable of predicting the AC overlay thickness within a reasonable level of accuracy.