Conversions of viscoelastic deflections of asphalt pavement under TSD load to elastic ones for pavement condition assessments

The Traffic Speed Deflectometer (TSD) facility has gained popularity in assessing asphalt pavement conditions due to its efficient testing process and minimal disruption to traffic flow. Current applications of TSD test results resemble those developed for the Falling Weight Deflectometer (FWD) test results, such as analysing the deflection basin shape and back-calculating the pavement layer modulus. However, the TSD facility induces more viscoelastic pavement deflections compared to FWD, primarily due to its rolling load. This research focuses on converting TSD's viscoelastic deflections under a wider range of loading conditions into elastic deflections under FWD load. This conversion aims to facilitate the use of FWD-based approaches for analysing TSD deflection data. The findings indicate that the converted TSD deflections generate more reasonable evaluation results, further emphasizing the necessity of converting TSD deflections to elastic ones. The models proposed in this research serve as valuable references for performing the viscoelastic-elastic deflection conversion.