One of the main problems in railway transport is noise emission which is often approached at both legislative and industrial level and the companies are tasked with identifying the best solutions for reducing noise level. In Europe, 10% of the population is exposed to noise levels which exceed the threshold of serious disturbance and social costs generated by road and railway traffic amount to EUR 40 Billion which means 0.4% of the European Union’s GDP.
The problem is not to prove the noxiousness of the noise on humans, which is universally known and acknowledged, but to establish the exact reach of this action, the implications it generates and to find solutions to protect people against noise pollution in areas strongly affected by phonic emissions”, declared Corneliu Luscalov, Senior Technical Executive of Vossloh Tehnica Feroviară and Infrastructure Director of the Romanian Railway Industry Association (AIF).
Railway infrastructure managers require innovative products and solutions for the construction of railways which deliver a high level of safety and economic feasibility.
The main source of noise generated by the traffic of a railway vehicle, “at speeds of up to 200 km/h is the noise generated by the rolling of wheels on the rail, the phenomena which occur at the wheel-rail contact emitting what we call “rolling noise”. With the optimisation of rolling speeds and the shift to high-speeds it was necessary to study the contribution that aerodynamic noise, which occurs at the friction of the car body at speeds of >200 km/h with air, has to the generation of railway noise”.
As regards the rolling noise, the components of the system (wheel, rail and sleeper) issue a certain energy quantity perceived as the noise.
Aside from the characteristics of the route of the rolling track and of the materials used for the development of the superstructure, noise is generated because of the faults of contact surfaces (wheels and rails).
“It is necessary that before the infrastructure is put in operation, tests and analyses on the quality and roughness of the rails are made as there are situations when even a new rail requires a first “grind”so as to level up surfaces and to remove the “soft” layer.
The final result of the process efficiency consists in reducing energy consumption as the reprofiling of the rail helps reduce noise level and rail wear. In this context, as regards the rolling stock, it is important that the bogie will “slide” on the rail which will obviously reduce friction forces (during braking energy consumption and the wear of the rail is higher) which cause the actual noise. It is also necessary that the wheel bogie geometry is checked periodically for both the passenger coaches and freight cars, as the traffic of wagons whose wheels are flawed or which have bad profiles damage the infrastructure. “Therefore, the permanent improvement of the condition of surfaces in contact during rolling (wheels and rails as even as possible) rail grinding and reprofiling of bogies whenever necessary is the top solution for reducing rolling noise levels and protecting railway infrastructures”, explains Luscalov.
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