Evaluation of the Rolling Wheel Deflectometer as a Structural Pavement Assessment Tool in Louisiana

The Rolling Wheel Deflectometer (RWD), which measures pavement surface deflection at traffic speed, offers the potential to characterize the structural conditions of the road network without major delays and in a cost-effective way. The objective of this study was to evaluate the repeatability of RWD deflections and to determine the effects of test speed and pavement conditions on the measured deflections. To achieve this objective, 16 different test sites representing a wide array of pavement conditions were tested. Results of the field testing program determined that the repeatability of RWD measurements was acceptable with an average coefficient of variation of 14% at a testing speed of 32 km/h. The influence of testing speed on the measured deflections was minimal. Since the test speed is restricted by the posted speed limit, testing can be conducted at different speeds while allowing for direct comparison of the measured deflections. RWD deflection measurements appear to properly reflect pavement conditions and structural integrity of the road network by providing for a greater average deflection and scattering for sites in poor conditions.