Franck Poisson, Deputy Manager Physics of the Railway System Department – SNCF
Environmental noise of the railway system: a new challenge for the future
The noise radiated by the railway system is a key issue in terms of integration of this mean of transport in the environment. The constant increase of the mobility demand leads to an increase of trains speed, of lines capacity… but, in the same time, the acoustic comfort of residents must be preserved .Indeed, in urban area as in the countryside, some residents are very close to the infrastructure and the noise radiated by the train pass by, the railway stations, the depots causes therefore annoyance for some people.
In Europe, residents are protected by some regulations. The environmental noise is limited at source and the dose of noise is limited at the receiver. Then, the mitigation measures can be implemented on the rolling stock, on the infrastructure, at the receiver and on operating conditions. Even if the rolling noise is the main source for a large train speed range, equipment noise can be the main source at low speed, in the stations, in the depots… and aerodynamic noise can be predominant for high speed trains. Then, mitigation measures must be implemented considering a system approach, including rolling stock constraints, infrastructure requirements and operating conditions.
Many mitigation measures have then to be foreseen in such a system approach and the cost of noise reduction becomes prohibitive for some projects. In such a context, a systematic and continuous noise reduction based on existing indicators cannot be conducted in the future. Then, SNCF has started an innovative approach to define the new challenges of the noise impact reduction. New research topics must be addressed like the definition of relevant indicators, the use of auralisation…
At the beginning of the presentation, regulation, main noise sources, existing mitigation measures will be briefly reminded. The question of the cost of the noise reduction will be addressed through an example. Then, the new approach carried out at SNCF will be presented.