# Assessment of Road Noise Pollution in Urban Residential Areas--A Case Study in Pitesti, Romania
## 4 Discussion  
Based on the measured values for 10 min with a sampling rate of 8 readings/second and intervals of 0.125 s, using Microsoft Excel program we can make the graphs of the noise level variation (LAF) in time, shown in Figures 11-13.  
Simultaneously with the noise measurements, traffic observations were made for the noise-generating traffic road flows.  
In the case of the traffic light intersection Maior Sontu a certain cyclicality is observed, this corresponds to the intermittent circulation that occurs on each band group [36; 38]. For the flow on the East-South arm in the vicinity of which the noise measurements were made, there are traffic observations of interest [38]:  
* The waiting line has very high values, so each vehicle waits at least 2 times for the Red light until it manages to cross the intersection on the Green light, so the demand is much higher than the capacity offered by the group of the 2 lanes, so that they circulate on the entire duration of the Green light;
* The vehicles turn left, the proportion of heavy vehicles is about 5%, and the road gradient is about 2%;
* Vehicles starts and runs in 1 st gear, at high engine load speed.  
The noise peaks are explained by the presence of large vehicles (dump trucks, concrete mixers, buses), which have a major contribution to the traffic road noise, when they start, but even while waiting for the Green light.  
In the case of the Podul Vilor roundabout, the measured noise is generated by the inlet flow on the western arm (fluently circulating vehicles, in medium acceleration regime) and through the conflict stream (cars moving at a constant speed) there are traffic observations of interest [35; 38]:  
* The entry volume on the West arm is 1100 PCU/hour, there are no heavy vehicles, and access is made in medium acceleration mode.
* The conflict flow corresponding to the West arm has the value of V\({}_{\text{conflict}}\) = 1100 veh-et/h, it is made up of vehicles moving at constant speed, in 1 st gear, and the proportion of heavy vehicles is about 5%.  
Thus, it is explained on the noise level graph the overlap of two noise values distributions: a distribution with average values of 70-75 dB and with peaks of noise around 80 dB, respectively, a less extended distribution, with average values of 65-70 dB.  
In the case of the Rectorship roundabout intersection, where it circulated with small accelerations in the \"Stop-and-go\" mode and where 5% of heavy vehicles were in the traffic (the traffic flow at the measurement point was 1200 PCU/hour) [39], the measured noise has average values in the range of 65-70 dB, but towards the end of the measurement range, these values have actually decreased, in the range of 60-65 dB, which is explained by the fact that the traffic on the roads from that moment began to decrease (above the peak value). There are also some noise level peaks, of which there are at least two aberrant values, since they correspond to the \"hello\" expressed by the horn, the noise measurement command (this is usually not the case, so they need to be excluded from the calculation excluded).  
The results obtained by the noise measurements made at the 3 road intersections are presented in the synoptic Table 1 for a comparative analysis.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Noise Parameter [dB(A)]** & **Major Sontu** & **Podul Vilor** & **Rectorship** \\ \hline L\({}_{\text{min}}\) & 62.1 & 60.8 & 60.9 \\ \hline L\({}_{90}\) & 65.5 & 64.0 & 63.1 \\ \hline L\({}_{50}\) & 68.6 & 66.4 & 66.0 \\ \hline L\({}_{10}\) & 73.1 & 70.4 & 69.3 \\ \hline \end{tabular}
\end{table}
Table 1: The noise indices values for the 3 road intersections.  
Figure 13: Graph of noise level LAF by time-Rectorship roundabout intersection.