A new grinding strategy to improve the acoustic properties of railway tracks

Abstract

Rail grinding is a special application of high-performance dry grinding, which combines a number of special characteristics, such as high feed speed, good surface roughness and waviness and a high material removal rate. Since beginning of the 20th century, rail grinding is used as a maintenance process and is essential for the increased rail life. In recent years, the surface roughness of railway tracks became increasingly important, especially with respect to the noise emissions. The rail grinding has a positive impact on the quality and life of the railway infrastructure, particularly on the driving comfort and safety. However, for the first weeks after the grinding, residents near railway lines have increased noise emissions from passing trains. This undesirable side-effect is a result of the rough surface left after the grinding process. Only through numerous train crossings are the generated roughness peaks gradually smoothed, whereby the noise emission is reduced. The wheel-rail contact is the dominant noise source at speeds between 50 and 250 km/h. Below those speeds, the propulsion noises outweigh and above 250 km/h the aerodynamic effects outweigh the wheel-rail contact noise emissions. In this paper, a newly developed rail grinding strategy is presented, which improves the roughness of the rail surface and, thus, delivers a reduction of noise emissions immediately after the grinding. The basic development of this new grinding technique was performed as a laboratory test, which will be presented in detail. Furthermore, for a better understanding of the process, the most important technological and kinematic variables are presented. The results of acoustic measurements on a track section, which has been ground with this new technology, will be presented.

Demiryolu yuvarlanma yüzeyi gürültüsü ve zemin titreşimi ve hat ilişkili azaltma önlemleri-güncel gelişmeler

“…Before the grinding, 11 train sets were measured in terms of acoustically, and 12 train sets after the process. The reduction of noise was achieved at 2 to 6 dB (A) for the overall noise level [94].…”

A rail corrugation index to characterize noise impacts and grinding effectiveness on rail transit systems

“…Considering noise as the independent variable, the regression equation can be interpreted as showing a 1 dB noise increase for each accumulated MGT after 91 dB. Substituting out the abscissa (MGT) in both equations yields a direct relationship between corrugation and noise, as shown in equation (6).…”

“…1,2 For rail asset managers-particularly those in the rail transit industry-the measurement, monitoring, and mitigation of rail corrugation is an important consideration in minimizing noise and vibration generated from rail corrugation, maintaining a state of good repair, and extending the life of rail and rolling stock components. 1,[3][4][5][6] Rail wear is the most common damage mechanism associated with rail corrugation (especially in transit systems). Plastic bending of the rail, plastic flow, and rolling contact fatigue (RCF) can also be causes of corrugation, though these phenomena can themselves be the consequences of corrugation.…”

Acoustic roughness measurement of railway tracks: Implementation of an optical measurement approach & possible improvements to the standard

“…According to Thompson, 6 the roughness of the two contact partners is directly coupled with the noise generation of the system. One possibility to reduce the noise emission caused by the rolling noise is the acoustic rail grinding as described by Kuffa et al 7 The acoustic roughness has to be measured in order to assess the quality of the grinding process, which is one possible application for these measurements according to Lutzenberger et al 8 Measuring the roughness from the moving train would offer possibilities to monitor the state of the network and for planning grinding operations and thus increasing efficiency of the maintenance process. As Verheijen’s 9 overview shows, direct measurements are mostly done manually and/or require a clear track.…”