The asphalt layer modulus is a key parameter for evaluating pavement structures with non-destructive testing (NDT). However, its measured value is influenced by the combined effects of traffic loading and long-term climate variations, making it difficult to assess how each factor contributes to pavement damage. In this paper, a practical method to separate these effects is introduced. The approach is based on the lateral distribution of wheel paths, for which deflection data were collected at various positions across the lane to backcalculate the corresponding modulus. Statistical analysis, including ANOVA and multiple comparison tests, showed a strong connection between measurement position—an indicator of cumulative traffic loading—and the modulus, with the modulus consistently decreasing under higher traffic exposure. Using these position-based differences, a quantitative model was developed to establish a baseline, traffic-free modulus. The main contribution of this work is a position-differential procedure that can effectively distinguish traffic-induced damage from long-term climate effects. The method's reliability and practical use were successfully demonstrated with data from the Long-Term Pavement Performance (LTPP) database.
Yang et al. (Mon,) studied this question.