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

Estimating Load Transfer Efficiency for Jointed Pavements from TSD Deflection Velocity Measurements

“…Scavone et al ( 30 ) revisited the principle underlying TSD pavement deflection velocity measurements. The authors found that the TSD provides reliable deflection velocity measurements and that, for jointed pavements, these measurements may contain information about the transverse joints’ LTE index.…”

“…A trial run of the new TSD took place at the MnROAD test track (owned and operated by the Minnesota Department of Transportation) in September 2021, where both flexible and jointed rigid pavement segments were tested. In Scavone et al (30), an in-depth analysis of the measurements at the jointed concrete sections within this testing site is presented: The analysis indicates that the 5 cm-resolution TSD measurements provide a clear depiction of the transverse joints' responses. One key finding of this study is that on jointed pavements (or pavements with discontinuities of any type), the commonly assumed relationship between deflection velocity and deflection slope (31), reproduced as equation 2, is no longer valid.…”

“…Moreover, the pre-processing stage of the TSD measurements could provide hints about the exact location of the transverse joint: on 1 m data processed by Basis Pursuit Denoising (28,29), the joint is within 1 m from the station at which a pulse response was recovered. Meanwhile, on 5 cm data, the highamplitude pulses on the v y signal indicate the location of the joint within 6 5 cm (30). Thus, given the approximate joint location, narrow lower and upper bounds for c (c min and c max ) can be defined for a given set of TSD v y measurements.…”

“…Instead, Scavone et al ( 30 ) showed that the v y measurements are constituted of two terms, one that relates to the slope of the deflection basin, plus an additional term that accounts for the changes in the shape of the deflection basin [ w ] after changes in the pavement structure such as layer thicknesses, material properties, or the presence of open cracks or joints. This term is mathematically noted as a partial derivative of the pavement deflection function w over time (equation 3).…”

“…This model has been chosen because of its relative simplicity in material characterization and its smaller computational cost, as compared with finite-element models ( 3 , 32 ). Moreover, Deep et al ( 3 ) pointed out that this model can reasonably simulate the rolling load of a heavy axle over jointed concrete, plus Scavone et al ( 30 ) showed that it can simulate the TSD’s v y measurements from jointed concrete pavements as well.…”