The application of the Hilbert-Huang transform to the analysis of inertial profiles of pavements

Inertial road profile measurements are widely used to assess the condition of existing pavements and monitor the quality control for smoothness of newly constructed pavements. A metric known as the International Roughness Index (IRI), computed from the inertial road profile quantifies the ride quality of the pavement. Within the inertial road profile, the variation of frequency-amplitude content versus distance is nonlinear and nonstationary. The HilbertHuang transform (HHT) and its Empirical Mode Decomposition (EMD) is well suited for nonlinear and nonstationary data. In the application of the HHT to inertial profile analysis, the intrinsic mode functions and their Hilbert transform can be used to: 1) represent the frequency/wavelength content of a profile; 2) filter the data in the distance domain in preparation for secondary analyses, and 3) compare two profiles and assess their similarities by performing simultaneous distance-frequency synchronisation.