Wavelet analysis of energy content in pavement roughness and truck dynamic axle loads

A wavelet approach is used to study the interaction between pavement roughness profile and heavy-truck axle dynamics. Profile and load variation are quantified in terms of their sum of squares or energy, in units of millimeters squared per meter and kilonewtons squared per meter, respectively. The dynamic axle load and pavement roughness profile data are decomposed into distinct frequency subbands and relative or percent energy is computed. The results are presented in the form of three-dimensional plots of relative dynamic load energy, pavement roughness energy, and pavement roughness frequency. They demonstrate the drastically different response of two types of suspensions to roughness excitation. Energy also was normalized by dividing by the length traveled, resulting in units of millimeters squared per meter and kilonewtons squared per meter for the profile and the dynamic load, respectively. The normalized energy results show a much higher dynamic load activity for the rubber suspension than for the air suspension. The normalized energy of load shows a high correlation with the normalized energy of the pavement roughness. The normalized energy of the pavement roughness profile shows a high correlation with the conventional international roughness index.