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A study on how correlation among FWD deflection data influences accuracy of the backcalculated pavement layer moduli is presented. FWD data were obtained from the Ministry of Construction, Road Test Section 609 and the data with stronger correlation were used in this study. Deflections without correlation and with similar correlation to the FWD data were generated using Monte Carlo simulation in order to investigate the effect of correlation on the backcalculation results. Furthermore, backcalculation analysis using theoretical deflection data with the same standard deviation but different correlations showed smaller variation in the backcalculation results for the deflection data with stronger correlation.

Results of structural evaluation analysis of pavement using FWD data from route 219 at Saito in Miyazaki Prefecture, Japan are presented. FWD is a dynamic loading device. DSGT, a dynamic analysis method and AASHTO and NIPPO which are static analysis methods, are used for the analysis. Subgrade modulus and effective pavament full depth AC thickness are backcalculated. A potential problem of whether static analysis (mostly used method) or dynamic analysis should be performed on the data is discussed in this paper by looking at the difference of results these two methods give in the analysis of FWD data.