Rolling Wheel Deflectometer

Rolling Wheel Deflectometer


Highway agencies need a safe, reliable, and high-speed technology for assessing in-place pavement structural conditions without impacting traffic. The technology is needed to address Federal performance management requirements (e.g., MAP-21) and to develop strategies for cost-effectively maintaining roadway networks. 


The Rolling Wheel Deflectometer (RWD) is an innovative device to perform efficient structural evaluation of highway networks. The RWD consists of a series of displacement lasers mounted on a custom-designed semi-trailer that collects nondestructive pavement deflections caused by an 18-kip single axle load.

The RWD uses triangulation lasers attached to an aluminum beam mounted beneath a custom-designed 53-ft semi-trailer. The trailer is sufficiently long to isolate the deflection basin produced by the RWD’s 18-kip, dual-tire, single axle from those produced by the RWD tractor. Four lasers work in conjunction to determine the maximum deflection produced by the RWD’s 18-kip, dual tire, single axle. Two additional lasers are used to measure the pavement deflection 15 inches forward of the wheels. A climate-controlled chamber maintains the measurement system at a constant temperature. The system also includes a distance-measuring instrument (DMI) to longitudinally reference collected data, an infrared thermometer to measure pavement surface temperature, and a global positioning system (GPS). 


The RWD operates at normal highway speeds and does not require lane closures or traffic control, and therefore is safer and less disruptive to the traveling public than traditional deflection measurement systems.

By providing a measure of pavement structural response, the RWD helps pavement engineers better assess in-place pavement conditions, more accurately identify pavement remaining service life, and enhance decision making related to pavement repairs. 


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Asset Management

Transportation Asset Management

Pavement and asset management, vehicle-based data collection, life cycle cost analysis, and construction and maintenance quality assurance systems... more