VTN: A VALIDATED METHOD TO SEPARATE TRACK AND VEHICLE NOISE AND TO ASSESS NOISE REDUCTION MEASURES

Within the European project STAIRRS, new methods and tools have been developed to address particular needs in the measurement and characterisation of railway noise. The Vibro-acoustic Track Noise method (VTN) is one of these methods. It is capable of separating the noise radiated by the train from the noise radiated by the track. The method uses a small number of acceleration signals from the rails and sleepers to calculate the energy radiation from the track. By measuring the total noise emitted by vehicle and track, it is possible to calculate the vehicle contribution as well. The method has been validated in the STAIRRS project and its accuracy has been assessed. Comparisons with results from TWINS calculations give further information about the accuracy of the method. The VTN-method has been programmed as a PC-based analysis tool. The tool has demonstrated its capabilities in the assessment of noise reduction measures. It clearly visualises the extent to which a measure acts on either the vehicle emission or the track emission. This makes it possible to assess the effect of that measure for combinations of other trains and tracks that were not tested. If the effect on the total noise is rather small (< 2 dB(A)), studying the VTN results can point out whether the effect is real. Other applications of VTN are acceptance and limit conformance testing and the collection of emission data (monitoring). The separated results make it possible to attribute the responsibility of railway noise emission to the track maintainer on the one hand and the train operator on the other hand.