Fuzhou World Bank Financed Projects Nanjiang Binlu, Phase-ii project of the Third Ring Road and Kuiqi Bridge environmental impact reportAssessment of traffic noise impact in operating period
Table 0.3 2 Vehicle flow in peak hours on Nanjiang Binlu
5.3.3.2
|
Vehicle type |
Equivalent level A of noise power LWA(dB(A) | |
LWA(V) |
LWA(lgV) | |
Light-duty vehicles |
89+0.3V |
66+24logV |
Medium-sized vehicles |
91+0.3V |
64+25logV |
Oversize vehicles |
96+0.3V |
71+24logV |
Motorcycles |
92+0.3V |
68+23logV |
In accordance with damping rule of point noise source in quasi-free noise field, noise level of various vehicles within the distance of 15m is calculated by the following formula:
Computing result as the following Table 3-4
Table 0.3 4 of various vehicle Unit: dB(A)
Vehicle type |
![]() |
|
75.5 |
Light-duty vehicles |
77.5 |
Medium-size vehicles |
82.5 |
Oversize vehicles |
78.5 |
Motorcycles |
|
Result of theoretical and experimental research testifies that friction effects produced by rough road surface and tires would not impact on noise level of oversize vehicles running with high speed basically, but will impact on noise level of light-duty vehicles, which shall be corrected according to the following Table 3-5.
Table 0.3 5 Corrected value of equivalent noise level A caused by road surface Unit: dB(A)
Road surface |
Corrected value ![]() |
Asphalt concrete road surface |
0 |
Cement concrete road surface and the ordinary roughness |
+3~+4 |
Seriously rough road surface |
+5~+6 |
When light-duty vehicles run on vertical grade, noise level will not change greatly, therefore correction of this part can be ignored. The motor will produce torque when medium heavy vehicles and oversize vehicles are upgrading, therefore noise of medium heavy vehicles and oversize vehicles upgrading will be louder than they run on level road, which increasing values as the following Table 3-6.
Table 0.3 6 Corrected value of noise of upgrading vehicle Unit: dB(A)
Grade(%) |
≤2 |
3~4 |
5~6 |
≥7 |
Corrected value ![]() |
0 |
+2 |
+3 |
+5 |
In case there are buildings on the two sides of the road (especially there are multi-story buildings and high-rise buildings on the two sides of the road, so reflection impact will be more obvious), superimposition of reflecting noise power produced by reflection of buildings will be put into consideration of noise value in forecasting point (as Figure 5.3-1). Because reflection makes noise level of forecasting point increased, its increment is shown by Reflection.
Buildings
S` mirror image noise S noise source x(m)
Figure 5.3- 1
From the figure, it is clear that noise wave of noise source S reflected by buildings to P is amount to noise wave radiated from mirror image noise source , that is
.
In case ≈1,
Reflcetion=3dB(A) ;
In case ≈1.4,
Reflection=2dB(A) ;
In case ≈2,
Reflection=1dB(A) ;
In case >2.5,
Reflection=0dB(A) 。
Although noise pollution of the front row buildings will be increased by buildings (especially multi-story buildings and high-rise buildings) on the two sides of the road, the first row buildings provide a good noise screen for the behind buildings. Different buildings have different height, so they will cause different damping values for different floor (that is different height) of the behind buildings; different building’s layout (it is parallel with the road, which is the reasonable layout and vertical with the road) will cause different damping value. Therefore, it is clear that confirmation of damping corrected value of equivalent noise level A caused by buildings on the two sides of the road is a complex process and it shall be corrected according to counting formula of noise insulation screen with limited length of line source.