Evaluation of Continuous Deflection Testing Using the Rolling Wheel Deflectometer in Louisiana

Abstract

The Rolling Wheel Deflectometer (RWD) offers the benefit to measure pavement deflection without causing any traffic interruption or compromising safety along the tested road segments. This paper presents a detailed field evaluation of the RWD system in Louisiana, in which 16 sites representing a wide array of pavement conditions were tested. Measurements were used to assess the repeatability of RWD measurements, the effect of truck speeds, and the relationship between RWD and (FWD) deflection measurements and pavement conditions. On the basis of the results of the experimental program, it was determined that the repeatability of RWD measurements was acceptable, with an average coefficient of variation at all test speeds of 15%. In addition, the influence of the testing speed on the measured deflections was minimal. The scattering and uniformity of the FWD and RWD data appear to follow closely the conditions of the roadway. Both test methods 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. The RWD deflection measurements were in general agreement with the FWD deflections measurements; however, the mean center deflections from RWD and FWD were statistically different for 15 of the 16 sites.