Enhancing Falling Weight Deflectometer (FWD) Testing: Comprehensive Review and Development of Robust Procedure in the United States

The Falling Weight Deflectometer (FWD) is a widely used nondestructive testing equipment for assessing the structural condition of pavements. The FWD measures the vertical deflection response of a pavement surface under a dynamic load applied by a falling weight. The deflection data collected from an FWD test can be used to determine the structural capacity of a pavement system, including the pavement layer thickness, elastic modulus, and subgrade strength, and to identify pavement areas that may require maintenance or rehabilitation. Despite the widespread use of the FWD, there are some concerns regarding the consistency and reliability of FWD test results. These inconsistencies have led to the need for a comprehensive evaluation of the current state of practice of FWD testing. The overall goal of this study was to conduct a comprehensive review of the literature and synthesize the best practices and areas of inconsistency in FWD testing for rehabilitation applications. This review will also allow for developing a robust FWD testing procedure across the states. Different agencies nationwide employ similar yet different FWD testing procedures, mainly in sensor configuration, load sequences, test plans, and data processing. Reviewing these testing procedures highlighted the similarities and differences and identified the potential items to improve. These potential items include but are not limited to sensor configuration, load sequences, test frequency, test spacing, and temperature measurements. This study will help state highway agencies and the industry identify best practices, improve consistency, enhance data comparability, increase efficiency, and improve decision-making for nationwide road construction and maintenance (or rehabilitation) projects.