Jordan Journal of Civil Engineering

Distress-based PSI Models for Asphalt Pavements of Rural Highways


Ghazi G. Al-Khateeb; Nagham Y. Khadour;


Pavement serviceability index (PSI) is one of the pavement performance measures that have been originally used in the AASHO (currently AASHTO) road test to evaluate the pavement condition. The PSI is highly correlated with roughness index which is currently used in the Mechanistic-Empirical Pavement Design method to predict pavement performance. Therefore, PSI is still considered an important index used for pavement performance evaluation. Experimental PSI models based on regression analysis were developed in this research study. The study involved thirty-five asphalt pavement sections with a 366-m (1200 ft) length representing thirty-five rural highways. Pavement distresses, including linear and fatigue cracking, rut depth, raveling, patching, debonding and potholes were measured. In addition, the present serviceability rating (PSR) and the roughness (measured by the slope variance (SV)) were obtained. The ride quality on a scale from 0 to 5 was used to provide the PSR, where 5 is the highest rating and 0 is the lowest rating. Two PSI regression models were developed that can be used for rough pavements (SV  500) and smooth pavements (SV  500), respectively. The most significant variables affecting the PSI were found to be rut depth, debonding and potholes (merged in one variable). Linear cracking and rut depth were found to be the second significant variable affecting PSI for rough pavements and smooth pavements, respectively. On the other hand, the slope variance had a relatively higher effect on the PSR of smooth pavements than that of rough pavements.


Asphalt pavements, Rural highways, Serviceability, PSR, PSI, Performance, Distress, Slope variance, Roughness.