## 3 The Production of a Noise Study for the Evaluation of Construction Site Noise
### A Case Study--Assessment of Noise from the Construction of an Office Building
#### 3.2.5 Noise Calculations  
The following formula applies to the simultaneous operation of sources of noise:  
\[L_{\wp}=10\lg\ (10^{\frac{L1}{10}}+10^{\frac{L2}{10}}+\ldots\ 10^{\frac{L4}{10}})\]  
where \(L_{1}\) to \(Ln\) are the sound power levels of the individual sources of noise and \(L_{\wp}\) is the sound power level of a group of sources. This calculation will take place within one calculation entry in Hluk plus software and the sound pressure value at the measured point is calculated taking into account attenuation according to distance and with the influence of acoustically significant elements in the surroundings. The input data for the calculation of the sound pressure level for the protected outdoor areas of buildings are sources of noise with the boundary conditions listed below. In Figure 4, sound power levels are entered into the calculations for construction machines which are expected to be deployed in this type of construction project. They include parallel deployment according to the technical stages and materials required for the construction of the investigated structures. The calculation will be influenced by the surrounding structures, especially the buildings in the Mirova Street line and elements in the gardens between Mirova and Cernovicka St. Reflective surfaces of buildings, as well as acoustically significant absorbent green areas, are entered. The calculation takes the terrain into account, especially the embankment on Cernovicka St. The calculation of isophones for the display of colour bands is performed for a height of 1.5 m above the ground. The construction machines are considered to be stationary sources of noise. In the outdoor areas, specific acoustic pressure level values are entered and calculated at the calculation points 2.0 m in front of the facades of the buildings in question. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Sources of Noise** & **Sound Power Level (dB)** \\ \hline
1. & Trucks & 90 \\
2. & Crawler excavators 12–40 tons & 103 \\
3. & Skid-steer loaders & 101 \\
4. & Crawler piling rig & 110 \\
5. & Excavator with a demolition hammer & \\
5. & Suspended hydraulic hammers, \(\diameter\) of the working & 114 \\  & tool up to 50 mm & \\
6. & Mobile crane & 95 \\
7. & Construction lift & 93 \\
8. & Vibrating roller & 106 \\
9. & Concrete mixer truck & 101 \\
10. & Crawler excavators (mini) 0.9–9 tons & 97 \\
11. & Pump & 100 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Expected sources of construction noise. Calculation 1: Demolition Work + Removal of Demolished Material, Machine: 5, 3, 1  
The following is a modeling of the acoustic situation and calculations for noise sources listed in Table 3.  
In Figures 5 and 6, we see the marked construction sites as noise sources and measuring points in the model. During the simultaneous deployment of machines, limit values are exceeded at four calculation points (4, 5, 6, 7) at the protected building facades, as we can see in Table 4.  
Measures: Separate deployment of machines. Removal of demolished material will take place when the main machine is not deployed. By separating the demolition process itself from the removal of material excavated during demolition, the noise from the demolition itself is lowered (according to Table 5) by only a maximum of 0.4 dB and no significant decrease in noise levels is achieved. In addition, the limit values are exceeded at four calculation points (4, 5, 6, 7) at the protected building facades. Figure 4: Acoustically significant elements in the investigated area. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Sources of Noise** & **Sound Power Level (dB)** \\ \hline
1. & Trucks & 90 \\
5. & Excavator with a demolition hammer & 114 \\  & Suspended hydraulic hammers & 101 \\
3. & Skid-steer loaders & 101 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Expected sources of construction noise. Figure 5: Acoustically significant elements of the investigated area, with the positions of construction machines as sources of noise, with simultaneous deployment.