## 4 Analysis  
### Relationship between Traffic Volume and Horn Honking  
The macroscopic analysis using the traffic counts were firstly carried out [40]. Correlation analysis between the total traffic volume and the frequency of horn use was examined at each intersection on each day of measurement. On weekdays, there was no significant correlation at any surveyed site (Intersection 1: \(r\) = 0.16, Intersection 2: \(r\) = 0.28, and Intersection 3: \(r\) = 0.02). On the weekend, significant correlations were obtained at two sites (Intersection 1: \(r\) = 0.72, \(p\) < 0.01; Intersection 2: \(r\) = 0.57, not significant; and Intersection 3: \(r\) = 0.90, \(p\) < 0.01). Table 5 presents the coefficient of correlation between the traffic volume of each vehicle type and the frequency of horn use. The results show significant correlations between the standard-sized vehicle traffic volume and the frequency of horn use on the weekend at all intersections and on the weekday at Intersection 2. The traffic volume of motorcycles significantly correlated with the frequency of horn use only at Intersection 3 (\(r\) = 0.90, \(p\) < 0.01). On weekdays, however, there was no relationship other than that for standard-sized vehicles at Intersection 2. Figure 4 shows scatter diagrams of the total traffic volume and the frequency of horn use during the measured 10 min in each hourly time zone, where the numbers next to data points represent time zones from 7:00 to 19:00. The frequency of horn use approximately increased as the total traffic volume increased at all surveyed sites. Such tendencies become clearer when removing the data for rush hours on weekdays (i.e., 8:00 and 17:00 or 18:00), in particular, at Intersections 1 and 3. As mentioned above, a high traffic volume during rush hours is supposed to relate to a high volume of motorcycles. The correlation between the total traffic volume and the frequency of horn use was analyzed using the data for weekdays and weekends with the data for rush hours eliminated (i.e., data for 9 h on a weekday and 12 h during the day on a weekend). Significant relationships were obtained for Intersections 1 and 3 (Intersection 1: \(r\) = 0.71, \(p\) < 0.01; Intersection 2: \(r\) = 0.35, not significant; and Intersection 3: \(r\) = 0.77, \(p\) < 0.01). To investigate the effect of the characteristics of the intersections on horn use, the relationship between the total traffic volume per lane at each intersection (i.e., the total traffic volume during the recorded 10 min of each hourly time zone was divided by the number of lanes entering the intersection) and the frequency of horn use was examined. Figure 5 shows scatter diagrams for the total traffic volume per lane and the frequency of horn use during the recorded 10 min in each hourly time zone. The result for the total measurement time, including rush hours, is displayed in Figure 5a, while the result obtained when removing the data for rush hours on weekdays is displayed in Figure 5b. These figures in Figure 5 show positive relationships between the frequency of horn use and the traffic volume per lane. Both relationships were statistically significant (Figure 5a: \(r\) = 0.63, \(p\) < 0.01; and Figure 5b: \(r\) = 0.74, \(p\) < 0.01). However, the linear relationship of the \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Types of Vehicles** & **Weekday** & **Weekend** \\ \hline \multirow{3}{*}{Intersection 1} & Motorcycle & \(-\)0.08 & 0.53 \\  & Standard & 0.54 & 0.72 ** \\  & Large & 0.13 & \(-\)0.04 \\ \hline \multirow{3}{*}{Intersection 2} & Motorcycle & 0.13 & 0.38 \\  & Standard & 0.65 * & 0.72 ** \\  & Large & \(-\)0.27 & 0.08 \\ \hline \multirow{3}{*}{Intersection 3} & Motorcycle & 0.00 & 0.90 ** \\  & Standard & 0.09 & 0.85 ** \\ \cline{1-1}  & Large & \(-\)0.22 & 0.70 ** \\ \hline \hline \end{tabular}  
* *: \(p\) < 0.05, **: \(p\) < 0.01.  
\end{table} 
Table 5: Correlation coefficient between the traffic volume of each type of vehicle and the frequency of horn use.