[[abstract]]The main objective of this study was to investigate the fundamental principles of flexible and rigid pavement backcalculation methodologies and their potential limitations. The two-layer backcalculation approach proposed by the 1993 AASHTO Design Guide for the structural evaluation of existing pavements was also adopted. The laboratory tested (or static) layer moduli were compared with the backcalculated (or dynamic) moduli using the Long-Term Pavement Performance (LTPP) database. Relatively high variability between the relationships of the static and the dynamic moduli was observed indicating that further research study is needed to improve the current state-of-the-art backcalculation approach. In addition, it was also found that slab thickness did have significant effects on the relationship of the backcalculated subgrade elastic modulus and the backcalculated modulus of subgrade reaction. Subsequently, a revised regression model was proposed for future practical applications.[[notice]]補正完畢[[incitationindex]]EI[[booktype]]紙
