Rolling Wheel Deflectometer for Pavement Evaluation

The Rolling Wheel Deflectometer (RWD) is an innovative device developed for the efficient, high-speed measurement of pavement structural response over a broad network of roads. It uses a series of lasers mounted beneath the bed of a custom-built 16-meter semi-trailer to measure a continuous profile of pavement deflections produced by the trailer's 8,164 kilogram (kg) single axle load. The RWD has recently moved from a research prototype to a production tool that has been used for network level pavement structural evaluation. This paper presents the results of a study that evaluated the structural capacity of 463 kilometers (km) of Pennsylvania Department of Transportation's (PennDOT's) local and arterial roads using the RWD and a Falling Weight Deflectometer (FWD) and comparison of the results to the estimated structural capacity stored in PennDOT's Roadway Management System (RMS). The structural capacity determinations from RWD data were based on a methodology developed by the Asphalt Institute (AI) that correlated deflections from a Benkleman Beam testing device to remaining pavement life. The structural capacity estimates from the FWD were based on conventional techniques described in the 1993 AASHTO Pavement Design Guide. The RMS estimates are based on pavement composition and age data. The results of the study indicated a good correlation between the estimates of remaining pavement life from the three methods, although significant scatter was observed in the data. All three methods clearly distinguished between the structural capacities of three groups of roads with known differences in pavement strength. The study verifies that the RWD is a useful tool for network level pavement evaluation for planning purposes.