An experimental assessment of ground-borne vibration impact of tramcars

Ground-borne vibrations from rail transit systems present challenges in urban areas due to their effects on structures and human comfort. This study introduces a falling mass impact setup to estimate the transmissibility between the track and a receiver in the surrounding area. This enables the calculation of the Line Source Transfer Mobility (LSTM), required by the U.S. Federal Transit Administration (FTA) to assess ground-borne vibrations from rail vehicles. The falling mass method offers higher energy input and better repeatability than traditional impact hammers, making it suitable for evaluating soil and building transmissibility even at long distances. Transfer mobilities obtained with this method are validated against hammer-based measurements. Vibration levels produced by a modern tramcar running at 10, 30, and 50 km/h are measured at various distances and normalised using the corresponding LSTM, in line with the FTA Detailed Assessment Method. Force Density Levels (FDLs) are calculated for each speed, with the highest values at 50 km/h. A strong consistency of FDLs across distances confirms the method’s robustness. This integrated experimental approach offers a reliable framework for characterising vibration sources and supports the assessment of vehicles and infrastructure planning in areas sensitive to vibration. • Experimental setup to characterise ground borne vibrations from tramcars. • Line source transfer mobility estimated via falling mass impact tests. • Impact force estimation validated experimentally. • Pass-by tests recorded at different distances. • Distance-independent force density confirms procedure robustness.