Correlation Comparison Testing between Traffic Speed Deflectometer and Falling Weight Deflectometer

Traffic Speed Deflectometer (TSD) has a significant potential to replace traditional deflection measuring instruments such as Falling Weight Deflectometer (FWD). However, due to the lack of experimental roads that can provide standard deflection values, quantitative evaluation of this advanced nondestructive measurement instrument still faces specific difficulties. For this reason, the paper designed and carried out three sets of comparison tests for two TSDs (manufactured by GreenWood of Denmark and Beijing Luxing of China, respectively) and one FWD (Model: CarlBro PRI2100): repeatability, speed variability, and correlation with FWD. When analyzing the experimental data, the representative deflection value of a section of road is proposed to replace the deflection of a single position, which avoids the problems caused by direct quantitative analysis of measured values. Especially in the correlation analysis, a data grouping method is proposed to divide the measurement values of three instruments on the same test pavement into 14 groups, and the correlation between the two TSDs and FWD is studied based on the correlation coefficients between the representative deflection values. The experimental results indicate that TSD, a new type of nondestructive testing instrument for road surfaces, has good repeatability, low speed dependence, and high correlation with FWD. The grouped pavement data can be characterized as multiple test roads with different deflection ranges, reducing the experimental test requirements of TSD. The new comparison method can avoid misjudgment caused by differences in measuring principles, operating procedures, data collection modes, and processing algorithms of instruments.