MOVING PAVEMENT DEFLECTION TESTING MEASUREMENTS

Non-destructive deflection testing has been an integral element of the structural evaluation of pavements for several decades. At present, Falling Weight Deflectometers (FWDs) represent the state-of-the-practice, but they are not without shortcomings. FWD deflection testing is a stop-andgo operation that requires lane closures, which in turn cause traffic disruptions and in turn create a safety hazard to personnel involved in the operation. It also implies that production rates are significantly less than a continuous one, which affects operational costs. To overcome these shortcomings, several organizations throughout the world have developed devices that can continuously measure pavement deflections. Recognizing the potential of these devices, the U.S. Federal Highway Administration (FHWA) undertook a study to: (1) assess the current state-of-thetechnology, (2) determine whether or not the current devices can be put to good practical use, and (3) determine the best uses of those devices identified as viable. In this study, three moving pavement deflection-testing devices were identified as viable – the Texas Rolling Dynamic Deflectometer (RDD), the ARA Rolling Weight Deflectometer (RWD) and the UK Traffic Speed Deflectometer (TSD). The first of these devices appears better suited for project level structural evaluations, while the remaining two appear to be better suited for network level applications, although some questions remain to be addressed. This paper discusses the major study topics – state-of-the technology, pavement applications and device specifications, and best uses of viable devices – as well as the major findings and conclusions to date.