Approach to the selection of means and methods of protection against the noise of wagon retarders

Abstract

   The strategy for the scientific and technological development of the Russian Railways Holding Company for the period up to 2025 and for the period up to 2030 includes the development and implementation of technologies and devices for noise reduction and active noise suppression in areas adjacent to railway transport.
   At railway transport enterprises, one of the sources of extremely high noise levels is car retarders. Active noise reduction measures have not yet been sufficiently developed for use in open areas. So far, acoustic baffles have been the only effective noise reduction measures that do not affect the safety or speed of the train unloading process.
   As a result of measurements carried out in the marshalling yard area, spectral noise levels, equivalent and maximum noise levels were obtained during the unbraking of unhitched wagons by claw-shaped wagon retarders. The measured noise levels exceed the permissible values both on the territory of the station and on the territory of the nearest residential area. The exceedance was established even in the presence of an acoustic screen. The acoustic screen, although not reducing noise levels to permissible values, has improved living conditions. The grouping of peak values of sound levels at frequencies of 2000 and 4000 Hz was noted, and the generation of high noise levels is not always related to the mass of the braked detachment.
   On the basis of the analysis of marshalling yards and measurement results, the principal calculation schemes for the calculation of noise attenuation from wagon retarders and options for selecting the combination of protection means are presented. The results of calculations of noise attenuation at the design point in the residential area show the need to adjust the calculation, because at some frequencies the results significantly exceed the standard calculation accuracy of ±3 dB.