Analysis of road surface profiles

This paper introduces a universal methodology for the analysis of discretely sampled sealed bituminous road profile data. Several hundred kilometers of Victorian (Australia) road profile data are analyzed in both the frequency and the amplitude domains. Road profile spectral characteristics are shown to be independent of road roughness. However, statistical analysis of the road elevation data shows them to be highly nonstationary, non-Gaussian processes that contain transients. Transients are difficult to locate when the data are analyzed in the road profile elevation domain itself, as they often occur within the Gaussian distribution. The road profile spatial acceleration is adopted as the preferred analysis domain, as roughness variations and transient events are identified with greater reliability and accuracy. Analysis of the spatial acceleration data enables the identification of large amplitude, short duration events (transients) as they occur extremely outside the Gaussian distribution. Higher order statistics, such as skewness and kurtosis, as well as the crest factor, are also used to detect transients (see Appendix I). It is shown that the road surface elevation becomes a stationary mean process with a nonstationary root-mean square when analyzed in the spatial acceleration domain.