Noise pollution during the night
According to the Environmental Noise Directive, environmental noise is defined as unwanted or harmful sound derived from human activity, including noise emitted by means of transport-road, rail and air traffic, and from sites of industrial activity (Directive 2002/49/EC 2002). This directive identifies road traffic noise as the predominant source of day-evening-night noise [6]. For locations L4 to L9, where devices were only powered during the night (in accordance with public lighting schedules), the traffic volume was compared between three defined periods (see Table 1): • Early night period: from 9 pm to 11 pm • Night period: from 2 am to 4 am • Early morning period: from 5 am to 6 am. The number of vehicles follows the expected trend, with more vehicles observed during the early hours of the night compared to the night and early morning periods. The values obtained for the early morning periods are smaller than those obtained during the night, suggesting that a higher volume of traffic starts after 7 am. The only location where this is not observed is L9, however the numbers are too small, and the difference is not significant (2 -> 5). The magnitude of the computed values is also as expected; locations L4 to L6 have higher traffic volumes, as they are all close to entry points to the city. On the other hand, the numbers for locations L7 to L9 are much lower, as they are closer to residential areas. This suggests that within residential areas, traffic noise is not a problem and residents can enjoy a peaceful and quiet night. It is worth noting that for L7, the poor lighting conditions (old sodium vapour lamps) affect the results and may explain the very low numbers observed for this location).
Location Early night Night
Early morning
L4
436
48
15
L5
254
14
4
L6
178
11
3
L7
20
2
2
L8
6
4
2
L9 5 Table 1. Median traffic counting per hour for locations L4-L9 for early night, night, and early morning. 34 2
12
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