Pavement Structural Evaluation At The Network Level

As State transportation departments consider structural adequacy as part of their routine pavement management system (PMS) activities by incorporating deflection testing, it is important to advance their practices from measuring deflection using falling weight deflectometers, which involves a slow, stop-and-go operation and requires lane closures, to a more viable alternative for network-level pavement management applications. The development of moving deflection testing devices that can measure pavement responses at traffic speeds represents this more viable alternative. The modern versions of the moving deflection testing devices that are actively used today include the Traffic Speed Deflectometer (TSD) and a Rolling Wheel Deflectometer (RWD). The goal of this project was 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 measuring at traffic speeds. Moreover, this measure needed to be robust enough in capturing the structural condition or deterioration of the pavement layer notwithstanding the seasonal and spatial variation in base and subgrade layers. As part of the project, a literature review was conducted, and questionnaires were developed for device manufacturers, owners, and users, which were then followed up by interviews. Both the TSD and RWD were found to be potentially viable devices. Based on this finding, a work plan was developed and implemented to evaluate if 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. Field evaluations and validation analyses were completed in accordance with the work plan. Ultimately, analysis methodologies and processes were developed for incorporating pavement structural information within highway agencies' PMS applications.