A comparative study of structural vibration transfer in low-floor tramway vehicles

In contrast to more standardized DMU/EMU systems, trams exhibit significantly greater design variability, requiring type-specific and occasionally side-dependent calibration of structural vibration transfer paths. Therefore, determining the structural and dynamic characteristics of various tram vehicles is essential for reliable vehicle-based vibration monitoring. This study compares structural vibration transfer paths in two low-floor tram bogie designs: the Solaris Tramino S105p with conventional wheelsets and the Končar TMK 2200 with independently mounted resilient wheels. Hammer impact tests were performed on mounted and free-standing configurations to determine Frequency response functions (FRFs) between excitation near the wheel–rail contact region and responses at the axle-box or bogie frame. The two tram designs showed similar resonance groups, but local FRF amplitudes differed by up to 10–20 dB. The TMK 2200 also exhibited clear left–right asymmetry, while cross-wheel-pair and cross-bogie transfer was strongest below about 250 Hz. The results provide a structural basis for future vehicle-based rail roughness and corrugation monitoring, although quantitative corrugation identification will require validation under operating conditions and inclusion of wheel–rail contact, track dynamics, vehicle speed and multiple-wheel excitation.