**2.2 Railway traffic noise**

The main sources of railway traffic noise are noise generated from:


There are several other significant sources of noise, apart from the main sources mentioned above, which are:


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.

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. 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. 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. The cause of this phenomenon is the constructive

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**Figure 4.**

*Traffic Noise*

used brakes.

notification signals.

*DOI: http://dx.doi.org/10.5772/intechopen.92892*

must glide, thus generating noise.

significant only at higher speeds [3].

affected by the negative effects of noise exposure.

• Noise caused by different types of engines.

The noise sources generated by the engine groups are:

• Propeller propulsion (classic or turbine engine).

• Noise caused by aircraft structure.

*Significant noise sources in the case of the high-speed train.*

airborne sound in buildings.

**2.3 Aircraft traffic noise**

• Turbojet engine.

• Turbofan engine.

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,

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

Noise from additional equipment is mostly generated by fans and their engines. Furthermore, it is important to mention the noise generated by the warning and

Aerodynamic noise is caused by the passage of the train through the airspace. 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

**Figure 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

Aircraft traffic also causes several environmental problems or in other words an increase of noise. Nowadays, when observing the rapid development of all types of traffic, especially aircraft traffic, it can be concluded that there has been a significant increase in noise levels. In particular, the population living near airports is

Aircraft noise can be divided into groups, which are shown in **Figure 5**:

### *Traffic Noise DOI: http://dx.doi.org/10.5772/intechopen.92892*

*Noise and Environment*

weight vehicles (LV <3.5 tons).

a.Vehicles traveling the railway.

**2.2 Railway traffic noise**

b.Maneuvers.

e.Motor trains.

f. Warning signals.

• Braking process.

system, and the ventilation system.

heating.

mentioned above, which are:

d.Electromotor trains.

c.Wagons.

tire noise.

engine (ICE) vehicle can be greater than 6 dB (A) at 10 km/h. Unfortunately, much later at higher speeds, both types of car become equally loud, mainly due to

and structure as described in the following paragraph.

When considering how traffic flow affects the subjective perception of noise levels, it can be concluded that it depends on the number of vehicles, their speed,

A traffic flow of 2000 vehicles per hour produces twice the perceived noise level than 200 vehicles per hour. If the traffic speed is 105 km/h, it produces twice the perceived noise level than the 50 km/h traffic flow. One heavy weight vehicle (HV > 3.5 tons) with a speed of 70 km/h creates a perceived noise level of 28 light-

The main sources of railway traffic noise are noise generated from:

There are several other significant sources of noise, apart from the main sources

• Propulsion systems for railway and railway vehicles.

• Interaction of wagon wheels, locomotives, and trains with rails.

• Aerodynamic noise, especially in the case of high-speed trains.

• Additional equipment such as ventilation, sirens, air-conditioning, and

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

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. 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. 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. The cause of this phenomenon is the constructive

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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.

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.

Noise from additional equipment is mostly generated by fans and their engines. Furthermore, it is important to mention the noise generated by the warning and notification signals.

Aerodynamic noise is caused by the passage of the train through the airspace. 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 [3].

**Figure 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.
