This paper describes the statistical properties of the pure random component of longitudinal road profile. The individual obstacles were removed from the road profile by median filtering approach. A total of 25,830 test sections records from the long-term pavement performance (LTPP) programme were analysed. The differences between asphalt concrete (AC) and cement concrete (CC) wearing courses were outlined. The comparison was shown on statistics (mean, median, standard deviation values) and probability density functions (PDFs) of contemporary used road indices (international roughness index (IRI), road elevation variance, power spectrum density (PSD) parameters in one-, two-and three-wavelength bands, etc.). The simulation study revealed the marked influence of obstacles on the road indices. The spectral properties of the pure random part were quantified.