Accuracy And Precision Evaluation Of Traffic Speed Pavement Deflection Devices

Pavement structural adequacy is considered an important aspect of the pavement management activities and can be incorporated by using surface pavement deflections. Continuous deflection technology, which has been around for several years, can potentially supplant single point deflection measurements provided by the Falling Weight Deflectometer (FWD). Previous studies have evaluated the traffic speed deflection devices (TSDD) accuracy and precision by comparing their results with FWD measurements. Although appropriate correlations and indices to compensate for the differences in load have been made, a direct comparison under the same loading conditions has not been reported in the literature. The goal of this Thesis is to establish a reliable measure of the structural condition of bound pavement layers above the unbound base layer as it deteriorates over time under traffic and environmental loading, based on moving pavement deflection technology, measured at traffic speeds (30 - 60 mph). Two devices, the Greenwood TSD and ARA RWD, were found to be potentially viable devices (Flintsch, 2014). Based on this findings, a work plan was developed and implemented to evaluate whether the two devices met a minimum set of specifications related to the structural evaluation of pavements at the network level, including accuracy and precision of deflection measurements, monitoring applied load, operating speed, and distance between deflection measurements. The modern versions of the TSDDs that are used in this study include the Greenwood Traffic Speed Deflectometer (TSD) and the Applied Research Associates, Inc. Rolling Wheel Deflectometer (RWD)