Model-supported analysis of comparative rolling noise measurements on two types of railway tracks

Rolling noise measurements of in-service trains have been carried out at the demonstrator of a new type of slab track (the "3MB" originally devised in the FP7 Capacity4Rail project) and an adjacent ballasted track section on the iron-ore line in Northern Sweden in May 2023. The analyses of the measurement data showed an increase in equivalent pass-by sound pressure levels (SPLs) at the slab track compared to the ballasted track, with, on average, about 2 dB observed at 7.5 m from the track. There was, however, a large spread in the results dependent on overall SPL, train speed, train type, and train individual. In addition to the pass-by measurements, a detailed characterization of track dynamics and rail roughness has been carried out. These latter measurements partially explain the observed differences in SPL, but more insight can be gained with a comprehensive model for rolling noise adapted to the conditions at the measurement site. In particular, the role of the rail roughness is investigated by simulations.