Reducing source noise

To reduce railway noise pollution, passive measures at the place of disturbance can be distinguished from active measures at the noise source. The most important passive methods used to reduce the impact of railway noise on the environment are noise protection walls and insulating windows, and most action plans and investments of the Member States concentrate on these methods.

However, the methods are only locally effective, requiring huge investments to protect wider parts of railway networks, as a report published by the European Parliament shows. The report was published in March 2012 on “Reducing Railway Noise Pollution”. In contrast, source-driven measures lower noise across the whole railway system if they are widely introduced. As an example, the problem of noisy rail freight cars can be reduced by the replacement of cast iron brake blocks by composite brake blocks (you can read more about this in our latest issue of Railway PRO Freight & Logistics). This is currently being investigated by the railway industry and would affect about 370,000 old freight wagons in Europe. Also, wheel absorbers, aerodynamic design of pantographs and noise insulation of traction equipment (for example, locomotive engines) are measures to reduce noise at source.
According to the authors of the report, noise should ideally be reduced at the source because these measures have a network-wide effect. Where track infrastructure causes increased noise levels (for example, structure-radiated noise from viaducts or curve squeal in narrow radius curves), or where the local environment is particularly sensitive to noise (for example, areas of natural beauty or urban environments with residences very close to the railway line) then additional track noise mitigation measures may be necessary. Such measures include friction modifiers, rail dampers, floating (or isolated) slab tracks and of course noise bunds and barriers in various heights. Vehicles and track should all be maintained to eliminate unnecessary sources of noise, for example, corrugation.
As regards the infrastructure, friction modifiers, rail dampers and slab track are cost-effective measures for reducing noise. In densely populated environments and highly trafficked railway sections, the use of noise barriers or coverings cannot be avoided. However, if there is a wide introduction of vehicle-related measures, the number of noise barriers or covers can shrink significantly.
Economic facilities, such as the differentiated charging of railways depending on noise emissions, can help stimulate the use of technology with reduced rolling stock noise emissions.

[ by Elena Ilie ]
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