## 4 Designing of the Appropriate Fairway Width
### Results of ES Model Simulation  
1. Simulation Overview  
In order to design an appropriate route width, the width of the route that is normally designed was analyzed and scenarios were constructed using various conditions to evaluate the risk according to the change in the vessel's traffic volume in the route width. Table 5 shows the details of the parameters set for different scenarios. In general, simulation evaluation reflects the number of vessels, vessel speed, vessel size, etc., based on the traffic survey results, and the traffic volume is reproduced by setting the time period with the most traffic. In this study, the concept of L-converted traffic was applied to evaluate the degree of risk according to the vessel traffic volume and the set fairway width. A vessel passing through a certain area per unit time follows a Poisson distribution [39]. In the target area, it was determined that 5-20 ships per hour from gate A and 5-15 ships per hour from gate B. The maximum fairway width in the approaching waters of the port analyzed above is 18.6 B, and since the width of the largest vessel passing through the target sea is about 46 m, the maximum fairway width in the approaching waters is about 855 m. In addition, the width of a typical TSS established along the coast of Korea is 5600-8500 m. Therefore, in this study the risk was evaluated using the ES model by generating the traffic volume of 5 to 20 ships per hour for each 1, 2, 4, 6, 8, and 10 km fairway width. \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & & & & & & \\ \cline{2-8} Degree of risk & \(-3\) & \(-2\) & \(-1\) & 0 & +1 & +2 & +3 \\ \cline{2-8}  & Very Safe & Safe & Little Safe & Middle & Little Dangerous & Dangerous & Very Dangerous \\ \hline \end{tabular}
\end{table} 
Table 4: Potential risk perceived by the operator. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Type**} & \multicolumn{8}{c}{**Width Range**} \\ \cline{2-8}  & **1 km** & **2 km** & **4 km** & **6 km** & **8 km** & **10 km** \\ \hline Traffic Volume & & & & & & & \\ Ship’s Speed & & & & & & & \\ Traffic Direction & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Variables used in the marine traffic simulation. Evaluation Criteria and Scenario  
Using the ES model, a risk assessment was conducted through various fairway width situations and changes in vessel traffic volume. According to Article 15 of the Maritime Safety Act of Korea, when the proportion with an ES value of 750 or higher is 10% or higher in the Maritime Traffic Safety Assessment conducted before the approval of the implementation of the maritime development project, it is judged that safety measures are necessary [39]. In this study, if the proportion with an ES value of 750 or higher was 10% or more of the total, the situation was judged to be dangerous and was set as a comparative index. Figure 9 shows the design of the ES model evaluation scenario for 1-10 km fairway widths with the different ship conditions. 3. Analysis of evaluation results  
In this chapter, the current traffic flow was reproduced based on the traffic volume in the evaluation target sea area analyzed in Figure 4 and the traffic flow analyzed in Figure 7. The L-converted traffic volume for the reference vessel (83 m) was applied to 5, 10, 15, and 20 ships, respectively, and a simulation was performed using a risk assessment model for a 1 km to 10 km width, which is the target of the evaluation. Figure 10 shows how the risk is distributed in each width of 1 km to 10 km for the hourly total environmental stress (ESA) value. When analyzing the risk distribution map from 1 km to 10 km, it was found that an ES value of 750 or higher occurs mostly for widths from 1 km to 4 km. Figure 9: Graph of the scenario for a safety assessment with the environmental stress model.