There are several factors that can cause the high level in noise exposure such as the
type of engines, exhaust systems and tires interacting with the road. Generally the
factors which influence the traffic noise are divided in four categories.
Figure 5: Factors affecting Traffic-Noise
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The first category consist of traffic parameters such as the speed, density,
composition, (one way street) driver’s behavior and traffic fluidity.
As the population increases, the traffic volume arises gradually.
Figure 6: Graph of Volume against Time
Image by Pervasive
The volume increases year by year. According to the analysis of the above graph the
volume roughly increasing by 60% per year.
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The second category consists of the road parameters such as the road design
(tunnels, cuts, enbankments), the gradients, degree of curvature, as well as the
nature and width of road surface. If the road pavement consists of stone then
an increased noise level will be generated.
Figure 4: Type of road surface
The graph below shows the sound pressure level for different types of vehicles in
different pavement type. It is shown that the vehicles travelling on an Open Graded
Asphalting Concrete (OGAC) and on Portland Cement Concrete (PCC) generate
high sound pressure level.
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The third category consists of the environmental parameter such as the
distance and height from the road of the recipient of noise, the condition of
ground between the road and point of intersection, the reflection of noise from
buildings along the road and the presence of natural screening.
Figure 5: The presence of natural screening on roads
Image by John Grayson
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The last category is the weather parameters such as the direction, speed of the
wind and the weather conditions such as the rain, snow and dry condition.