2. Applying the TSI formulae together with the multiple-interpolations method to determine track decay rates using train pass-by measurements (in06_55

In the TSI document a reliable method to determine track decay rates has been provided. The method consists of acquiring mechanical FRF data at a track site, post-processing the measured data, and the presenting the estimate. The calculation formulae of the TSI method assume that vibration waves in the rail can be measured as a single propagating vertical bending wave and a single propagating lateral bending wave of the rail acting as a simple beam. This paper is to report the possibility to apply the TSI formulae to determine track decay rates using train pass-by measurements. The simulation calculations have shown that (1) the data interpolation can be done accurately provided that the assumptions behind the TSI formulae are good approximations; thus (2) the data interpolation can further be done as many times as the accuracy requires and the calculation error will then become any small. Using the measured train pass-by data, in which some other types of waves and/or the cross interactions between the different banding waves may have some effect but small, the track decay rates determined using the TSI formulae and the multiple-interpolations method seem to be trustworthy