Assessment of Continuous Pavement Deflection Measuring Technologies

Abstract

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Capabilities and Potential Applications of Continuous Pavement Deflection Measuring Devices

“…The findings of the research are documented in SHRP 2 Report S2-R06F-RW-1 (Flintsch et al 2013), as well as in several publications Bryce et al 2012;Katicha et al and 2013b The project occurred in two phases. The first phase, documented in Flintsch et al (2012) and Flintsch et al (2013), evaluated several continuous deflectometers and conclude that two currently available devices, the rolling wheel deflectometer (RWD) and the traffic speed deflectometer (TSD), were the most promising devices in terms of meeting user's needs. User needs were determined as a result through a survey of several transportation professionals to determine the key engineering parameters that they wish to derive from deflection testing (Flintsch et al 2013).…”

“…The first phase, documented in Flintsch et al (2012) and Flintsch et al (2013), evaluated several continuous deflectometers and conclude that two currently available devices, the rolling wheel deflectometer (RWD) and the traffic speed deflectometer (TSD), were the most promising devices in terms of meeting user's needs. User needs were determined as a result through a survey of several transportation professionals to determine the key engineering parameters that they wish to derive from deflection testing (Flintsch et al 2013). Furthermore, a working definition of a continuous deflection device was adopted and included those devices that could collect data at intervals of approximately 300 mm (1 ft) or less by using load levels typical of trucks [i.e., 40 to 50 kN (9 to 11 kips) per wheel or load assembly], as well as devices that could operate without the need for the vehicle or the measuring device to remain stationary and devices that could operate at normal traffic speed with no traffic management.…”

“…The data came from testing that occurred in the United States for the RWD, as well as the United Kingdom for the TSD (details of the test sites can be found in Flintsch et al (2013)). Furthermore, repeatability of the RWD and TSD as well as comparisons with the FWD can be found in (Flintsch et al , 2013Bryce et al 2012;Katicha et al 2012Katicha et al , 2013aKaticha et al and 2013b. Phase two also investigated the potential application of continuous deflection devices for network level pavement management using measurements obtained from the TSD, which will be discussed in more detail in later sections of this paper.…”

“…In order to reduce measurement noise and file sizes, the average deflection over a 160 m distance (0.1 mi) is typically reported. Additional details about the RWD measurement process can be found in Flintsch et al (2013), Steele (2005a) and Steele (2005b). The TSD ( Figure 2) is a device that measures the pavement deflection velocity using Doppler lasers that are spaced at specific distances from the applied load.…”

“…These devices are modified trucks that measure pavement response to an applied load while travelling at or near traffic speed. Different available devices and measurement technologies were extensively evaluated as part of a recent Strategic Highway Research Program 2 (SHRP 2) project number R06(F) (Flintsch et al 2013). Continuous deflectometers have the potential to allow agencies to evaluate the structural capacity of large portions of their pavement networks in a considerably shorter time period than when the FWD is used, and also minimize the need for traffic control during testing.…”