Analysis of the wavelength content of the longitudinal profiles for C-LTPP test sections

A new approach for pavement longitudinal profile analysis is described in this paper. In this approach, based on a simple moving average filtering technique, the results are expressed in terms of the proportion of the calculated international roughness index associated with different wavelengths of pavement surface deformations. The new approach has been successfully used in the assessment of the performance of Canadian Long-Term Pavement Performance (C-LTPP) test sites. The proposed analysis approach can help in identifying the source of problems causing pavement roughness. It can thus help in identifying the proper pavement rehabilitation technique. The new analysis approach has also helped in assessing the performance of the different rehabilitation techniques used in C-LTPP. It was found that 80-130 mm thick overlays give the best results in reducing roughness associated with short wavelength deformations. The benefit of these overlays is, however, limited to several years. Moreover, overlays do not have any significant impact on long wavelength deformations. It has also been found that long wavelength distortions tend to dominate the longitudinal profiles of thin pavement structures or pavements built on soft fine grained soils. Short wavelength distortions are dominant in longitudinal profiles of cracked thick pavement structures or that are built on strong soils.