Noise: Noise mapping
Noise Mapping England research project
A research study on rail and wheel roughness - implications for noise mapping based on the Calculation of Railway Noise procedure
To assist in the implementation of the Environmental Noise Directive (2002/49/EC) (END) and the development of a National Ambient Noise Strategy (NANS), this report was prepared by AEA Technology (AEAT).
Calculation of Railway Noise (CRN) was originally developed as the method to be used during the implementation of the Noise Insulation (Railways and other Guided Transport Systems) Regulations 1996. These Regulations apply to new or improved railways. Calculation of Railway Noise is also one of the methods to be used during the application of the DfT Guidance on Methods for Multi-Modal Studies. Consequently, it is a method that is available for use when noise mapping railways.
It has been known that one of the factors that affects the generation of noise from railway movements is the roughness of the surface of the rail (the railhead). However, as CRN applies primarily to new railways, the methodology assumes a generally smooth railhead and, in fact, the procedure does not include the facility to take account of any variation in railhead roughness.
Techniques have only recently become available to enable the measurement of railhead roughness over wide areas of the network to be made. That work has shown that at some locations, the roughness of the track could increase significantly the noise generated from the railway compared with what would be expected from applying the methodology in Calculation of Railway Noise.
Railhead roughness can be tackled by increasing the grinding of the railhead and, as such, could form part of any action plans developed under the terms of the END or the NANS. However, if the railway noise maps were produced using CRN, it would not be possible to reflect in the modelling the effect of railhead roughness, nor the benefit that might be achieved from increasing the frequency of grinding.
This report explores these issues and provides information on:
- Measuring wheel and rail roughness;
- The development and control of railhead and wheel roughness;
- The study undertaken to determine whether CRN could be modified to reflect the railhead roughness;
- The application of such modifications; and
- Some outline implications of adopting various types of railhead grinding strategies
The results of the study suggest that it may be possible to adapt CRN to take account of railhead roughness when mapping railway noise.
It should be noted that although a modified CRN method has been identified in this study, the implementation of both the Noise Insulation Regulations and the application of the GOMMMS guidance should continue to use the currently published version of the Calculation of Railway Noise.
The full report is available to download
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file (610 KB)
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Contacting Defra
If you want further information that is not covered by these pages, you can contact us by e-mail at noise@defra.gsi.gov.uk
Page published: 10 March 2004