Track-independent vehicle indicator for ground-borne noise and vibration classification: validation and site transposition method

Within the SILVARSTAR/QuieterRail framework, the track-independent vehicle indicator (TVI) is derived from railhead force density, obtained indirectly from measured ground vibration during train passages and a site-specific line source transfer mobility (LSTM). Two formulations are defined, one linked to feelable ground-borne vibration, and one linked to ground-borne noise. Frequency weightings are applied to mimic human sensitivity to each. Vehicle performance is classified by comparing relative TVI differences. Comparisons with overall frequency-weighted vibration and noise levels showed that TVI differences reproduce inter-vehicle trends consistently across distances and sites. Two parametric studies with the MOTIV model aim to consolidate the TVI framework and quantify how vehicle parameters affect the TVIs. The first uses a controlled set of mainline vehicles to isolate the influence of individual parameters. The second covers urban rolling stock and, unlike the mainline study, includes models with combined vehicle changes to support realistic like-for-like comparisons across typical urban trains. Robustness to site variability is then assessed by recomputing force densities for multiple track/soil configurations. To reduce sensitivity to track parameters, a transposition approach is introduced. A band-byband transposition correction factor (TCF), based on differences in overall vibration, anchors TVI-based classification to a designated reference site. It is shown that transposition generally tightens the noise TVI inter-vehicle differences, while the effect is smaller and mixed for vibration TVI that is already quite robust.