Comparison of methods for estimating track decay rate

Abstract

The track decay rate (TDR) is used to qualify the acoustic performance of a track for pass-by noise tests, in transposition from one site to another, and to update rolling noise models. Analysis is presented using a track vibration model to show the differences between the result of method defined in EN 15461 and the decay rate of individual waves. The TDR obtained from the EN method is consistently higher than the decay rate of the principal wave in the rail. A reduction of measurement effort is possible by reducing the measurement grid from the 29 points defined in EN 15461; even a set of 9 points leads to only small differences in the TDR obtained from the simulations. Using a sensor position above a sleeper instead of at mid-span leads to potentially large differences. Additionally, simulations to represent the pass-by method are shown for comparison. This method gives consistently higher TDR results than the EN method. The effect of reflections between wheels is shown to be significant for soft rail pads; the increase of pad and ballast stiffness under load has a significant effect.

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Identifiers

ORCID for David Thompson: orcid.org/0000-0002-7964-5906

ORCID for Martin Toward: orcid.org/0000-0001-7334-4355

ORCID for Giacomo Squicciarini: orcid.org/0000-0003-2437-6398

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