【正文】 400Hz range is promised by the steel sleepers by around 2 to 3dB. The results for the passenger trains shown in (Fig. 5) indicate the same trends as 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 10 the freight trains. The 1kHz peak in the spectrum of noise from the south track is probably equipment noise from the trains travelling in this direction. 5 Conclusions The bridge is shown to give much higher levels of noise than nearby track at grade. The installation of resilient baseplates has reduced the overall level difference from about 11dBA to about 8dBA. However, the baseplates make of greater noise reduction of 5 to 10dB where the bridge structureradiated noise dominates between 80 and 400Hz. The Norbert model has predicted the reduction in noise in the 80 400Hz bands reasonably well although the measured spectra are smoother than those predicted. In the 630 and 800Hz bands, where the rail noise dominates, Norbert has predicted a reduction that is greater than that actually achieved. This leaves the overall noise reduction to be only about 3dB (4dB predicted) for the freight and passenger trains alike. The removal of the hanging steel sleepers was worthwhile to gain the full benefit of the structure noise reduction Promising locations for similar bridge treatments will be identified according to their cost benefit. The baseplates from different suppliers to the same specification produce similar results. 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 11 Acknowledgements The authors are grateful to the SBB for permission to publish this work. References [1] Bewes, ., Thompson, ., Jones, ., Wang, A.: Calculation of noise from railway bridges and viaducts: Experimental validation of a rapid calculation model. Journal of Sound and Vibration 293, 933–943 (2021) [2] Janssens, ., Thompson, .: A calculation model for the noise from steel railway bridges. Journal of Sound and Vibration 193, 295–305 (1996) [3] Harrison, ., Thompson, ., Jones, .: The calculation of noise from railway viaducts and bridges. Proc. Institution Mechanical Engineers, Part F (Journal of rail and rapid transit) 214, 125–134 (2021) [4] Thompson, ., Hemsworth, B., Vincent, N.: Experimental validation of the TWINS prediction program for rolling noise, part 1: Description of the model and method. Journal of Sound and Vibration 193, 123–135 (1996) [5] Thompson, ., Jones, .: A review of the modelling of wheel/rail noise method. Journal of Sound and Vibration 231(3), 519–536 (2021) [6] Bewes, O., Thompson, ., Jones, .: Calculation of noise from railway bridges: The mobility of beams at high frequencies. Structural dynamics: Recent advances. In: Proceedings of the 8th International conference, Institute of Sound and Vibration Research, Southampton, (paper 64 on CD ROM) July 14–16 (2021) [7] Jones, ., Thompson, .: Acoustic analysis of Burgdorf bridge, ISVR contract report no 06/03, University of Southampton (2021) [8] Jones, ., Thompson, ., Diehl, .: The use of decay rates to analyse the performance of railway track in rolling noise generation. Journal of Sound and Vibration 293(3–5), 485–495 (2021) [9] Janssens, ., Dittrich, ., de Beer, ., Jones, .: Railway noise 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 12 measurement method for passby noise, total effective roughness, transfer functions and track spatial decay. Journal of Sound and Vibration 293(35), 1007–1028 (2021) [10] Bouvet, P., Vincent, N., Coblenz, A., Demilly, F.: Optimisation of resilient wheels for rolling noise control. Journal of Sound and Vibration 231(3), 765–777 (2021) [11] Muff, W., Grolimund amp。 (a) north track。? (b) south track ( , calculated from the slower freight trains , SF/ST project bined roughness for tread braked and (lower) for disc braked wheel。 Fax: +41 (0)51 220 5014 2 University of Southampton, ISVR, Highfield Southampton, SO17 1BJ, Southampton, UK Tel.: +44 (0) 2380 593224。stli1, . Jones2, and . Thompson2 1 Swiss Federal Railways SBB, IFWPS, Schanzenstr. 5 CH3000 Bern 65, Switzerland Tel.: +41 (0)51 220 4699。 right side, decay rates of the rail. An estimation of the bined effective roughness (. bined wheel and rail roughness with the contact filter already accounted for) is needed for the predictions. A method to determine the bined roughness from rail vibration measurements under traffic is described in reference [9]. This method uses the spectrum of vibration during a train passby and three correction factors. It has been applied to rail vibration measured by the SBB. The roughness is a function of the brake type of the train. Here, the most important trains to consider are the cast iron block treadbrake