11/28/2023 0 Comments Denver traffic speeds![]() įigure 4 shows the noise sources of a high-speed train, apart from ground vibrations resulting from its passage and the conversion of structural sound to airborne sound in buildings. The noise level generated by air turbulence at or near the train surface in motion is logarithmically proportional to the train speed therefore aerodynamic noise is significant only at higher speeds. Furthermore, it is important to mention the noise generated by the warning and notification signals.Īerodynamic noise is caused by the passage of the train through the airspace. ![]() Noise from additional equipment is mostly generated by fans and their engines. The noise generated by the braking process, in addition to the roughness of the wheels and track contact surfaces, depends significantly on the type and form of used brakes. The cause of this phenomenon is the constructive nature of the wagons themselves, in which the wheels are fixed with parallel axles, which is why the outer wheels, when crossing a longer path than the inner ones, must glide, thus generating noise. When driving through the railway curves, the wheels make more noise, not only due to rolling but also due to slipping of the metal wheels, which can be observed as creaking along the railway track. When moving on straight railway sections, the noise is mainly generated as a result of the roughness of the wheel and rail surfaces, i.e., from their friction. Wheel-rail interaction generates dominant noise in railway vehicles and depends directly on the speed of movement and the geometric configuration of the railway track. ![]() On the propulsion system, noise is mainly generated by the operation of the traction engine (suction and exhaust process in the case of the diesel engine which is also the noisiest type of engine), the engine cooling system, the transmission system, and the ventilation system. Interaction of wagon wheels, locomotives, and trains with rails.Īdditional equipment such as ventilation, sirens, air-conditioning, and heating.Īerodynamic noise, especially in the case of high-speed trains. ![]() Propulsion systems for railway and railway vehicles. There are several other significant sources of noise, apart from the main sources mentioned above, which are: The main sources of railway traffic noise are noise generated from: Unfortunately, much later at higher speeds, both types of car become equally loud, mainly due to tire noise. For example, the noise level difference between an electric vehicle and an internal combustion engine (ICE) vehicle can be greater than 6 dB (A) at 10 km/h. However, at low speeds, electric vehicles produce very small levels of noise, i.e., in current acoustic urban environments, they are practically inaudible. In terms of noise pollution, electric vehicles represent the future, especially when compared to vehicles with an internal combustion engine (see Figure 3). This type of noise depends on the type of road surface, the tire construction, and finally the speed and driving style. Tire noise occurs when the tires and road surfaces come into contact. The fan noise is generated due to the operation of the fans in the vehicle, and the fans generally produce a broadband noise. Noise from the exhaust system is created by the sudden release of gas into the exhaust system itself in order to open the exhaust valve. The suction system noise is caused by the opening and closing of the suction valves, and furthermore the intensity of such noise depends on the mode of operation of the engine, the speed of the engine itself, and the type of air filter. The engine noise depends on the engine volume, speed, and capacity. Engine noise is created during the process of compression and expansion in the engine, which creates engine vibrations which then emit noise.
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