Fuzhou World Bank Financed Projects Nanjiang Binlu, Phase-ii project of the Third Ring Road and Kuiqi Bridge environmental impact report

Assessment of traffic noise impact in operating period

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5.3 Assessment of traffic noise impact in operating period

5.3.1 Forecasting method of traffic noise

Nanjiang Binlu is composed of ground road mainly. Because there are different road structures and buildings on the two sides, noise fields produced by traffic noise near the road are totally different and very complex, especially compound road composed of overhead roads and ground roads. Noises produced by starting, speed-up, braking, wheeling and upgrading of motorcycles on the road are different, which causes more complex noise fields, therefore it will be considered as uniform running, as well as vehicle flow and proportion of vehicle type are considered the same as in our forecasting. According to vehicle flow of different road sections in different forecasting years and design parameter of the road, range and degree of traffic noise on the two sides of the road, which on different sections in the daytime and nighttime, in the year of 2005, 2010 and 2020, will be forecasted.

5.3.2 Forecasting mode of traffic noise

Cadna/A, the software used in environmental noise forecasting of Germany, recommended by Environment Engineering Assessment Center of State Environmental Protection Administration is adopted as forecasting mode of traffic noise.

Superimposing value (Leq) of forecasting value of traffic noise (Leq_Traffic) and value of environmental background (Leq_Background) of Nanjiang Binlu:

5.3.3 Confirmation of each parameter in forecasting mode

5.3.3.1 Proportion of vehicle type and vehicle flow

According to forecasting of vehicle flow and road design standard of Nanjiang Binlu explained in Nanjiang Binlu Feasibility Study Report, proportion of vehicle type of Nanjiang Binlu is listed on the following Table 3-1. Vehicle speed is 50km/h; vehicle flow in daytime (within 16 hours) accounts for 87.3%; vehicle flow in nighttime (within 8 hours) accounts for 13%. Vehicle flow on each road section in peak hours of the year of 2005, 2010, and 2020 on Nanjiang Binlu is distributed as in the following Table 3-2.

Table 0.3 1 Proportion of vehicle type on Nanjiang Binlu

Year	Passenger car	Taxi	Passenger bus	Light truck	Lorry	Total
2005	26	5	17	13	39	100
2010	30	7	17	12	34	100
2020	35	8	14	12	31	100

Table 0.3 2 Vehicle flow in peak hours on Nanjiang Binlu

Section description	2005		2010		2020
Section description	Daytime	Nighttime	Daytime	Nighttime	Daytime	Nighttime
Section from Sanqiao to Kuiqi	1041	156	1549	232	1462	219
Section from Sanqiao to Siqiao	1559	233	2221	332	2045	306

5.3.3.2 Value of Each Kind of Vehicle

According to inland research, relationship between equivalent level A of noise efficacy and vehicle speed of various motorcycles in our country is as the following Table 3-3.

Table 0.3 3 Relationship between equivalent noise efficacy level A and vehicle speed of various vehicles

Vehicle type	Equivalent level A of noise power LWA(dB(A)
Vehicle type	L_WA(V)	L_WA(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

Note: vehicle with speed of 20～80km/h is adaptable.

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	(60km/h)
	75.5
Light-duty vehicles	77.5
Medium-size vehicles	82.5
Oversize vehicles	78.5
Motorcycles

5.3.3.3 Modified Value of Road Surface

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

According to design plan of Fuzhou Nanjiang Binlu, its road surface is covered by asphalt, therefore its corrected value of noise is 0dB(A) .

5.3.3.4 Corrected value of vertical grade

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

The biggest vertical grade of Fuzhou Nanjiang Binlu is <5%, therefore its corrected value is +2dB(A) .

_{5.3.3.5 Corrected value} _{Reflection caused by reflection of buildings on the two sides of the road}

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.

y(m) Forecasting point p(x，y)

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) 。

5.3.3.6 Damping corrected value of equivalent noise level A caused by buildings on the two sides of the road

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.

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