Based on well-known rolling noise principles, the pass-by rolling noise of trains can be decomposed into a vehicle transfer function, a track transfer function, wheel roughness, rail roughness and train speed. Using these quantities, it is possible to separate vehicle and track radiation. In addition, it is possible to characterize a vehicle independently from the track using its transfer function and roughness. Similarly, the track is characterized by its own roughness and transfer function. It has been shown that vehicle data could be transferred from one site to another and that track data could be transferred from one vehicle to another. Furthermore, measurement methods have been developed that derive these quantities from fairly simple trackside pass-by measurements using, in principle, one accelerometer, a wheel trigger device and one microphone. These include the combined total effective roughness from the rail vibration signal during pass-by and the vibro-acoustic transfer function between effective roughness and sound pressure from a pass-by. The accuracy was about +/- 3 dB for individual one-third octave bands. Based on pass-by data estimates can be obtained for the transfer function of the track, by using a pass-by of a quiet 'reference vehicle'; the spatial decay of the track, giving agreement of +/- 1.5 dB with conventional hammer measurements; the transfer function of the vehicle, by using energy difference or a quiet 'reference track'; and on a smooth track, wheel roughness for individual wheels, all wheels on a vehicle or a group of vehicles. A validation exercise has shown that using these measured functions, the overall A-weighted pass-by sound pressure level of various combinations of vehicles and tracks could be reconstructed with an accuracy of +/- 1 dB. The approach presented is only valid for rolling noise. When there are significant levels from other noise sources, such as traction, braking, squealing or aerodynamic noise, these should be dealt with separately.


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    Title :

    Railway noise measurement method for pass-by noise, total effective roughness, transfer functions and track spatial decay


    Additional title:

    Verfahren zur Messung des Eisenbahnpassierlärms, effektive Gesamtrauigkeit, Übertragungsfunktion und räumliches Abklingen des Gleises


    Contributors:


    Publication date :

    2006


    Size :

    22 Seiten, 14 Bilder, 5 Tabellen, 21 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English