## 2 Materials and Methods
### Measurement of Equivalent Continuous Sound Level  
In the first stage of the study, field measurements were taken of the equivalent sound pressure level (\(L_{Aq}\)), a key indicator of noise pollution. The direct measurement method was employed, providing an accurate representation of the environmental acoustic character. This approach allows for the most precise depiction of the acoustic climate. The study utilized the direct measurement method alongside sampling. The measurements were carried out in accordance with ISO 1996-1:2016 [49] and ISO 1996-2:2017 [50] standards. The measurements were conducted under suitable atmospheric conditions: the ambient temperature was above 5 \({}^{\circ}\)C, the wind speed did not exceed 5 m\(\cdot\)s\({}^{-1}\), there was no precipitation, and the road surface was dry. The field tests were conducted between 26 May and 30 May 2024, from 8:00 a.m. to 4:00 p.m. The measurement time at each measuring point was five minutes. A four-channel SVAN 958 meter (Svantek, Poland) was used for measurements--a first-class device that includes a preamplifier, 1/2'' measurement microphone, 10-m microphone cable, windscreen, tripod, and calibrator (1000 Hz, 114 dB). The specifications are presented in Table 1. The device was configured with the following parameters: the elementary signal recording time was 5 min, correction characteristic A, FAST response time, a measuring range of 110 dB, and an integration time set to 1 s. During measurements, the microphone was positioned 1.5 m above the measuring surface and perpendicular to the axis of the vehicles. The sound pressure level, expressed in dB and corrected according to the A frequency response curve (\(L_{pA}\)), is calculated as follows:  
\[L_{pA}=10 log\frac{p_{A}}{p_{0}} \tag{1}\]  
where:  
\(p_{A}\)--sound pressure level corrected according to the A-frequency characteristic, \(p_{0}\)--reference pressure level of 2 \(\times\) 10\({}^{-5}\) Pa, hearing threshold for 1000 Hz. Before and after the measurements, the sound level meter was checked in the environmental conditions under which the tests were conducted using a calibrated class I acoustic calibrator, SV 33B, 1000 Hz/114 dB. If the meter did not pass the test, it was recalibrated. The background noise level during calibration did not exceed 75 dB. During the field tests, the meter was calibrated at least once before starting measurements in each test area, meaning at least once for every nine measurements. The remaining parameters of the meter were checked with similar frequency. The measurements focused on traffic noise but also included natural environmental noises such as birds singing and the sound of the wind. The background noise was recorded when there was no vehicle traffic and was included in the environmental analysis. The contribution of the acoustic background was subtracted from the total sound energy level based on Equation (2). \[L_{AqT}=10 log_{10}\bigg{(}10^{\frac{L_{total}}{10}}-10^{\frac{L_{background}}{10 }}\bigg{)} \tag{2}\]  
where: \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Characteristics** \\ \hline Compliance standards & IEC 61672-1:2013 [51] (sound, class 1), ISO \\  & 8041-1:2017 [52] (vibration) \\ Frequency range & 0.5 Hz–20 kHz \\ Microphone type & MK 255, 50 mV/Pa \\ Total SPL measurement range & 16 dBA RMS \(\div\) 140 dB Peak \\ Linear operating range in accordance with & 26 dB \(L_{\text{eq}}\) \(\div\) 140 dB Peak \\ IEC 61672 & \(\sim\)16 dB \\ Internal noise & \(<\)16 dB \\ Corrective filters & A, C, Z (for sound), G (for vibrations) \\ Time constants & Slow, Fast, Impulse \\ Frequency analysis & Analysis in 1/1 and 1/3 octave bands \\ Internal memory & 32 MB of memory \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical specifications of the SVAN 958A sound and vibration meter (Svantek, Poland). \(L_{AeqT}\)--sound level,  
\(L_{total}\)--total sound level including background noise,  
\(L_{background}\)--background noise level.