## 2 Materials and Methods
### Modelling Noise  
The CadnaA program was used to model the noise emissions from road traffic in the vicinity of the intersection in Zilina City. Three scenarios of real external environments around intersections in the built-up area were modeled: (a) a three-arm intersection before reconstruction (T_16); (b) a roundabout after reconstruction (R_17); (c) a roundabout after five years of use (R_22). The models captured the change in the noise load in the outdoor environment around different intersection types. CadnaA is a software program that is used for the calculation and assessment of noise and air pollution. The software calculates and predicts the noise impact in the vicinity of commercial and industrial sites, sports and leisure facilities, and traffic systems like roads and railways, airports and landing strips, and other noisy facilities. CadnaA is suitable for noise prediction in local studies as well as for detailed analyses of noise mapping scenarios in cities. In the CadnaA program, it is possible to choose from several methods of calculating noise levels from different sources. For the modeling of noise propagation in the vicinity  
Figure 4: Photos of the measuring set sound analyzer (NOR-121, accuracy Class 0) when measuring roundabout noise emissions at R2. of the proposed intersections, we used the \"Nouvelle Methode de Prevision du Bruit\" (NMPB-1996). The emission parameter used in the NMPB-1996 is the \(A\)-weighted sound power level per octave band \(L_{Au,i}\) of a point like sub-source \(S_{i}\) in dB(A) [45]. This level is calculated from  
\[L_{Au,i}=10\lg\left(10^{\frac{(E_{VL}+10\lg Q_{VL})}{10}}+10^{\frac{(E_{PL}+10 \lg Q_{PL})}{10}}\right)+20 dB+10\lg l_{i}+R(i) \tag{4}\]  
where \(E_{VL}\) is the sound power level of the light vehicles in dB(A), \(Q_{VL}\) is the traffic number of the light vehicles (max. mass m < 3500 kg) in veh/h, \(E_{PL}\) is the sound power level of heavy vehicles in dB(A), \(Q_{PL}\) is the number of heavy vehicles (max. mass m \(\geq\) 3500 kg) in veh/h, \(l_{i}\) is the length of the sub-source \(S_{i}\) in m, \(R(i)\) is the octave values of the reference spectrum for road noise in dB(A), and \(i\) is the running number of octaves. In CadnaA, the overall traffic flow \(Q\) (in vehicles/hour) and the percentage of heavy vehicles \(p\%\) are specified. The relationships between those figures and the ones described above are  
\[Q=Q_{VL}+Q_{PL} \tag{5}\]  
\[p\%_{o}=\frac{Q_{PL}}{Q} \tag{6}\]  
The calculated emission parameter is the \(A\)-weighted total sound power level per unit length \(L^{\prime}_{Au,i}\) in dB(A), which is determined according to the modified equation:  
\[L^{\prime}_{Au,i}=10\lg\left(10^{\frac{(E_{VL}+10\lg Q_{VL})}{10}}+10^{\frac{ (E_{PL}+10\lg Q_{PL})}{10}}\right)+20 dB+\Psi\left[\text{dB(A)}\right] \tag{7}\]  
This value includes the corrections for the vehicle type, traffic flow type, road gradient, and road surface \(\Psi\) (see below). The respective data for the hourly traffic \(Q\) (veh/h) and the truck proportion \(p\) (%) are given in the next table (Table 3). MDTD and the truck proportion \(p\) data were taken from real measurements of the traffic volume attained during the noise measurement. The truck proportion \(p\) (%) was used for all three modeled scenarios (T_16, R_17 and R_22) (Table 3), and was evaluated from real measurements of traffic flow. The traffic volume determined by direct measurements with the radar counting device was 15,687 vehicles/24 h passing through the three-arm intersection (T_16) and 16,520 vehicles/24 h passing through the roundabout (R_17) on the selected working day (Table 4). Traffic volume was monitored during the noise measurement day. These data on the traffic volume and its direction were used for the noise load model in the vicinity of the intersection. The traffic volume measured at the roundabout in 2017 was also used for the model of the roundabout (R_22) in 2022.