Three‐Dimensional Numerical Analysis of Traffic‐Induced Vibrations: Investigating the Effects of Road Surface Unevenness and Soil Stiffness

In the present paper, a three‐dimensional (3D) numerical model was established to assess the ground vibrations induced by vehicles traversing road surface irregularities. The equations of motion for the coupled system, comprising a multibody vehicle model and road unevenness profiles, were first solved to determine the dynamic vehicle loads. These loads were subsequently applied to a 3D finite difference model (FDM) to compute the resulting ground vibrations, which were validated against referential experimental data. The proposed numerical model was then utilized to examine the effects of various types of road unevenness, including global road roughness and traffic calming measures. Additionally, the influence of vehicle speed and subsoil stiffness was evaluated. The results indicate that greater road surface undulation correlates with higher vibration levels. Poor road conditions were found to generate significant vibrations that may exceed human comfort and structural thresholds at greater distances from the road, particularly in cases involving soft subsoils. Specific geometries of traffic calming measures, such as speed bumps, were shown to produce noticeable ground vibrations; for instance, a short hump could generate vibrations exceeding structural and human comfort thresholds at distances of up to 15 and 23 m, respectively. Moreover, higher vehicle speed was shown to amplify both the impact load and its frequency bandwidth, leading to higher ground vibration levels. In contrast, stiffer subsoils were observed to significantly reduce vibration levels; a 60% reduction in vibrations was achieved when the subsoil stiffness was increased by a factor of 10. The developed 3D model provides an effective tool for engineers and urban planners to mitigate traffic‐induced vibrations by optimizing road geometries, setback distances, soil stiffness, and maintenance schedules, ensuring compliance with human comfort and structural safety thresholds.