Investigation of the Rolling Wheel Deflectometer as a Network-Level Pavement Structural Evaluation Tool

About the report:

The Virginia Department of Transportation (VDOT) currently uses the results of automated surface distress surveys to assist in developing pavement maintenance strategies for its interstate and primary roadways.  Totaling nearly 27,000 lane-miles, these roadways consist of flexible, rigid, and composite (flexible over rigid) pavements.  These video-based surface distress data consist of quantities of distress that are visible in the pavement surface.  Obtaining structural data from falling weight deflectometer (FWD) testing has only recently been implemented at the network level. 

A growing area of interest in pavements research is developing new and faster technologies that are well suited for nondestructively assessing the pavement structure without causing delays to the traveling public.  One recently developed system, the rolling wheel deflectometer (RWD), measures the response from one-half of an 18-kip single-axle load traveling at normal highway speeds.  This technology can measure deflections for approximately 200 to 300 lane-miles per day, which is approximately 10 times the production of traditionally used FWD testing.  The primary advantages of using RWD are twofold: the testing can be conducted at highway speeds for increased safety, and the loading by the RWD is thought to replicate better the actual dynamic effects on pavements caused by heavy vehicle loading.  A potential application might be to use the RWD to pre-screen the pavement network to identify areas where more detailed investigations are needed (e.g., by traditional FWD testing).

This report provides the results of RWD testing on three Virginia routes and a comparison of the deflection results obtained with RWD and FWD testing on sections of I-64 and I-81.  The RWD provided deflection measurements over long distances at or near highway speeds with minimal interruption to the highway users, and the RWD and FWD deflection results were not well correlated.  Further, the standard deviation of the RWD deflection results fluctuated with changes in surface mix type.  For these reasons, the study recommends that VDOT not pursue additional RWD testing on roadways that are expected to have low deflection values and are likely to be uniform in structural cross-section (i.e., conditions that might be expected on interstate facilities).

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