Investigation of Ground-Borne Vibrations Generated by Metro Trains on Elevated Structures

Ground-borne vibrations generated by metro train operations on elevated structures pose significant concerns related to human annoyance in urban environments. Although previous studies have primarily relied on theoretical approaches, limited field-based evidence exists to quantify vibration attenuation through the complete train–track–structure–soil system. This study addresses this gap through simultaneous in situ measurements conducted at both structural (rail track, plinth, slab deck, and pier) and ground levels using accelerometers and geophones, with uncertainties accounted for throughout the monitoring period. The results indicate a 23 % reduction in vibration acceleration from the rail track to the pier, a 31 % reduction in vibration velocity between 2 and 12 m from the pier centerline, and dominant vibration components higher than 40 Hz. Uncertainty analysis revealed variations of 2–19 VdB in Unit I and 0.5–5 VdB in Unit II, whereas peak responses showed reductions of 95 % in acceleration from the rail track to the pier and 96 % in peak velocity from 2 to 12 m from the pier centerline. Overall, vibration velocity decreased by nearly 78 % from the track to the ground. Comparison with existing empirical models indicated deviations within 1.5–10 %, and a simplified trendline equation is proposed for the preliminary assessment of ground-borne vibration.