On the TSD deflection velocity measurements: a revision to the current state of the art and discussion over its applicability for concrete pavement assessment

ABSTRACT

The fourth-generation TSD can provide pavement deflection data at a much higher rate than previous versions. This data is valuable to evaluate the structural health of the transverse joints in concrete pavements. Analysis of TSD measurements from a jointed pavement segment allowed the detection of a mistake in the way the TSD's deflection velocity [v_y] data is processed to get deflection slope [S] estimates: We state and prove that the well-known direct relationship between v_y and S is only valid in limited scenarios, and particularly invalid nearby the transverse joints. We highlight that v_y is made up of two components, one of which is related to S and that at the vicinity of a discontinuity in the pavement structure, the second component of v_y gains relevance and explains the discrepancy between v_y and S. Also, it is shown that TSD v_y measurements gathered near a joint resemble v_y signals simulated with a linear elastic model. Thus, this study brings new insight into the contents of a TSD v_y measurement and buttresses the TSD’s reliability as a v_y measurement device. Plus, it suggests that further research should develop TSD data interpretation schemes based on v_y instead of deflection slopes and depths.

KEYWORDS:

• TSD
• concrete
• joints
• deflection

Disclosure statement

This research came about as part of the Transportation Pooled Fund project TPF 5-385: “Pavement Structural Evaluation with Traffic Speed Deflection Devices (TSDDs),” supported by the Federal Highway Administration, U.S. Department of Transportation. No potential conflict of interest was reported by the author(s).