Extensive measurements have been performed with the goal of collecting model data for the majority of vehicles and track systems that are currently in use in Switzerland. Pass-by measurements of totally 14500 vehicles with train speeds ranging from 50 to 200 km/h were performed at 18 measurement sites. The situation at each measurement site was described by the track decay rate, the local rail roughness and the local sound propagation conditions, determined with loudspeaker experiments. Pass-bys of trains were measured according to ISO 3095 using sound pressure microphones at 4 positions and acceleration sensors attached to each rail. At two measurement sites additionally a line array was used to gather information about secondary sound sources. Besides regular trains, two test trains with known wheel roughness were measured at each site. The figures below show a map with the measurement locations and a result of an array measurement.
Overview of the locations of the test sites on the railway lines Lausanne Freiburg and Mattstetten Rothrist.
Measurement site with an acoustical camera during a pass-by of a test train.
Distribution of sound intensity in the 1 kHz third-octave band for a locomotive type Lok 2000 and a coach type EW IV at 100 km/h. The figures on top of the picture indicate the resulting sound power for four ranges of height (Courtesy of Sulzer Innotec).