Development of comprehensive deflection parameters to evaluate the structural capacity of flexible pavements at the network level

Abstract

Pavement deflection has been used widely as a nondestructive technique to evaluate the structural capacity of pavements at both network and project levels. Current devices include Falling Weight Deflectometer (FWD) and the Deflectograph, which can record the deflection bowl shape. Utilizing these devices, a load is applied on the pavement surface and deflections at several lateral locations are recorded. Various transportation agencies use several evaluation methods to evaluate the integrity of the pavement layers. Most of these up-to-date developed indices are exclusively based on either central deflections or one deflection point along FWD deflection bowl. However, no standardized method is available that utilizes the full FWD deflection bowl. This study aims to introduce new comprehensive pavement layer deflection and deflection bowl area parameters that are based on the entire FWD deflection bowl rather than one single deflection point and to relate the developed parameters to the field measured distress data. Required data for the study were extracted from the Long-Term Pavement Performance (LTPP) database. Thirty-five different pavement sections in the State of Texas were utilized in the study. Four comprehensive deflection parameters were developed. In addition, a scale was developed that may be utilized for the overall pavement structural condition evaluation. The developed parameters as well as the scale were found to be well correlated to field performance of considered pavement sections. The newly developed parameters can also be easily implemented in pavement management databases (PMS) that would help state department of transportation (DOTs) in making more informed decisions about the most suitable maintenance strategy.