## 4 Analysis
### Noise Level in Situations with and without Honking  
A previous study employed the noise prediction model to estimate the effects of honking on the acoustic environment [44]. However, in the present study, a single-point measurement was conducted because it was considered that such a simple measurement would be sufficient to approximately determine the impact of horn use on the acoustic environment near intersections (or the difference between when the horn use occurred and when it did not occur) without using noise maps or other prediction methods.  
To determine the impact of horn use on the acoustic environment around intersections, we calculated the equivalent continuous A-weighted sound pressure level (\(L_{\text{Aeq,10 min}}\)) and the maximum noise level (\(L_{\text{Amax}}\)) of the RTN, both with and without the use of horns, by vehicles. Data management software (RION AS-60) was employed to calculate the \(L_{\text{Aeq,10 min}}\) and \(L_{\text{Amax}}\) without the use of horns. The data for horn sounds were removed from the initial data, and then both acoustic indices were recalculated. Figure 7 displays the variations in total traffic volume and \(L_{\text{Aeq,10 min}}\) during the measurement time for each intersection and each measurement day. The similar results for \(L_{\text{Amax}}\) are displayed in Figure 8.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Types of Situations When Horns Were Used**} & \multicolumn{1}{c}{**Without**} \\ \cline{2-6}  & **(1) Cutting** & **(2)** & **(3)** & **(4) Stopping** & **(5)** & **Honking** \\  & **In Line** & **Slowness** & **Sudden Stop** & **State (Delay)** & **Unclear** & \\ \hline Intersection 1 & 10 & 4 & 3 & 27 & 55 & 117 \\ Intersection 2 & 2 & 3 & 1 & 24 & 14 & 34 \\ Intersection 3 & 2 & 6 & 0 & 6 & 29 & 95 \\ \hline \hline \end{tabular}
\end{table}
Table 8: The number of each situation with and without horn use in green light phases when left turns were possible.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & & **Number of** & **Mean Start** & \\  & & **Situations** & **Delay Time (S)** & _p-Value_ \\ \hline \multirow{2}{*}{Intersection 1} & With honking & 27 & 4.6 & \\  & Without honking & 117 & 2.2 & \\ \hline \multirow{2}{*}{Intersection 2} & With honking & 24 & 6.2 & \\  & Without honking & 34 & 2.0 & \\ \hline \multirow{2}{*}{Intersection 3} & With honking & 6 & 4.2 & \\  & Without honking & 95 & 2.1 & \\ \hline \multirow{2}{*}{All intersections} & With honking & 57 & 5.2 & \\  & Without honking & 246 & 2.2 & \\ \hline \hline \end{tabular}
\end{table}
Table 9: Mean start delay times with and without horn use.  
Figure 8: Temporal variations of the total traffic volume and \(L_{\text{Amax}}\).  
Figure 7: Temporal variations of the total traffic volume and \(L_{\text{Aeq,10 min}}\).  
Significant relationships between \(L_{\text{Aeq,10 min}}\) and total traffic volume were found for all measurements, except one weekday at Intersection 1 (Intersection 1: \(r_{\text{weekday}}=-0.05\), not significant; \(r_{\text{weekend}}=0.81\), \(p<0.01\); Intersection 2: \(r_{\text{weekday}}=0.87\), \(p<0.01\); \(r_{\text{weekend}}=0.76\), \(p<0.01\); and Intersection 3: \(r_{\text{weekday}}=0.62\), \(p<0.05\); \(r_{\text{weekend}}=0.85\), \(p<0.01\)). Although the values of \(L_{\text{Aeq,10 min}}\) when the noise level data of honking were removed were very similar to those when such data were not removed, \(L_{\text{Amax}}\) sometimes decreased when the noise level data of honking were removed in situations when \(L_{\text{Aeq,10 min}}\) values were relatively low.