# Assessment of Road Noise Pollution in Urban Residential Areas--A Case Study in Pitesti, Romania
## 3 Results
### Noise Indices Determination at Road Intersections in the Central Area of Pitesti
#### 3.2.1 The Maior Sontu Traffic Light Intersection (Maior Sontu Street-Targul Din Vale Street)  
The measurements were made on a working day, around 4.30 p.m. at the Maior Sontu-Targul din Vale traffic light intersection, according to the road noise measurements regulations, in the immediate vicinity of the vehicles flows entering through the East arm of the intersection, on the pedestrian sidewalk, as shown in Figure 4.  
Figure 3: The 3 road intersections in the Pitesti central area where noise measurements were taken. The calibration of the noise measurement chain was performed for Level A filter Fast (LAF), which is the instantaneous noise level measured with the weighted filter A (used for the noise pollution produced by vehicles), with rapid mediation of the results. With the specific equipment for road noise measuring (the microphone placed at the distance and height prescribed by the standard) there was a continuous recording of noise. The total noise recording time was 10 min. The noise sampling interval was 0.125 s, which means a sampling frequency of 8 records per second-a high enough frequency to consider continuous recording over time. The LAF values were obtained by measurement, these being the noise level weighted according to scale A, specific to the road noise. The results processing requires the increasing ordering of the obtained values and the grouping of the values on intervals with the 2 dB size, then using the Matlab program, the histogram of the distribution of LAF values is made (Figure 5). We observe a specific image of the normal distribution (Gauss's bell), but also with values of the noise level exceeding the normal distribution in the field of higher values (at a visual estimate, there are values with about 4-6 standard deviations above the average). The processing of the obtained results consisted in the determination of the physical and psychophysical indicators for the distribution of values of the noise level obtained after the measurements (Figure 6). For simplicity, the usual L notation for noise level was used. Figure 4: Noise measurement at the Maior Sontu traffic light intersection: (**a**) placement of the sound level meter in the proximity of the traffic road flow; (**b**) road noise recording and analyzing. Figure 5: Instantaneous noise level histogram (LAF)–Maior Sontu. The physical indicators of the measured noise were determined: L\({}_{10}\) = 73.1 dB, L\({}_{50}\) = 68.6 dB; L\({}_{90}\) = 65.5 dB. In addition, the extreme values are identified: L\({}_{\min}\) = 62.1 dB; L\({}_{\max}\) = 91.9 dB. The results processing involved the increasing ordering of the obtained values and their grouping at intervals of 2 dB size, obtaining the LAF values distribution histogram. These statistical indicators can be highlighted on the linear graph of the cumulative noise level frequencies (Figure 6). Based on these values, using the calculation relationships defined at the methodology presentation, the values of the physical and psychophysical indices of the traffic road noise were determined. * Noise climate, c: \[\text{c}=7.6\text{ dB}.\]
* Psychophysical index of noise pollution level, \(L_{\text{NP}}\): \[L_{\text{NP}}=77.2\text{ dB}.\]
* Psychophysical index of traffic noise, \(T\)NI: \[T\)NI = 65.9 dB.
* The average noise level, L\({}_{\text{m}}\): \[\text{L}_{\text{m}}=69.3\text{ dB}.\]
* Noise level standard deviation, \(\sigma\): \[\sigma=3.8\text{ dB}.\]
* The psychophysical index, L\({}_{\text{eq}}\) [dB], was calculated automatically by the dedicated software for noise analysis, its value being: L\({}_{\text{eq}}\) = 72.7 dB. It is a value lower than the one previously measured, at 5.30 p.m. (73.5 dB), which is explained by the fact that although the capacity of the East arm is exceeded by the traffic demand in both situations, at 2.00 p.m. the proportion in the traffic composition of heavy vehicles is lower.