Moving Pavement Deflection Testing Devices: State-of-the-Technology and Best Uses
Pavement management systems (PMS) have historically relied on distress (e.g., cracking, and rutting) and roughness (e.g., International Roughness Index or IRI) as key pavement performance indicators in the decisions-making process. Both are important indicators that merit emphasis within the PMS process, but they are not the only ones. Structural adequacy, for example, is another important pavement performance indicator that is critical to making rational pavement rehabilitation decisions. And indeed, more and more highway agencies in the USA are incorporating deflection testing as part of their routine PMS activities. Deflection testing for the structural evaluation of pavements has been around for decades. Falling Weight Deflectometers (FWDs) represent the state-of-the-practice in pavement deflection testing; however, FWD testing is a stop-and-go operation that requires lane closures (hence can cause traffic disruptions and create a safety hazard) and that has limited production rates. To overcome these shortcomings, a number of organizations have developed moving pavement deflection testing devices. Recognizing the potential benefits of these devices, the Federal Highway Administration commissioned Fugro Consultants, Inc., to undertake a study to determine whether the current devices can be put to good practical use and, if so, how best to utilize the devices. This paper presents the results of the study. Highlights from a state-of-the-technology review into moving pavement deflection measurements are presented; three devices were identified as viable. Findings and conclusions from a technology assessment of the three viable devices are also presented, including the best uses for these devices.