PAVEMENT DEFLECTION INVENTORY (ITS USE IN FATIGUE CRACK PREDICTIONS)

Pavement deflection data have been used in the past by the Alaska Department of Transportation and Public Facilities (ADTPF) to monitor the performance of their highways. In an earlier study these data were used to develop a model for predicting fatigue cracks in the pavements. Deflection measurements at the center of the load were used for this purpose. Two years ago, the ADTPF acquired a Falling Weight Deflectometer (FWD) to measure pavement deflections. This equipment, besides measuring the deflection at the center of the load, also records deflections at six other points away from the center of the load. The users of the FWD have reported that the measurements obtained with the help of this equipment can be used to define the shape of the deflection basin. Further, it was reported that the deflection basin was a better indicator of the damage potential to highway surfaces than the single measurement of surface deflection under the load center. Based on the above mentioned experience it was expected that the fatigue damage prediction model could be improved significantly if FWD data were used in place of deflections at the center of the load. Therefore, the primary objective of this study was to develop a model for fatigue crack prediction using the FWD data.