## 4 Re-Designing of the Appropriate Fairway Width
### Results of ES Model Simulation for Fairway Expansion  
As a result of analyzing the risk of ship collision according to the ES Model and the risk of grounding according to IWRAP Mk II for the target fairway, we found that the risk of collision was high in the Yeosu fairway, Masan fairway, and Gadeok fairway, whereas the grounding risk was good. In this study, the evaluation of the grounding probability was based on islands, obstacles, and low water areas farther than the end line of the fairway,  
Figure 9: (**a**) Distribution map of ES \(\geq\) 750 for the Wando fairway, (**b**) the Yeosu fairway, (**c**) the Masan fairway, and (**d**) the Gadeok fairway. without considering the fairway line. Therefore, the fairway can be expanded to some extent to the islands, obstacles, and low-depth areas, which form the standard of grounding for each fairway. However, if the vessel's navigation area spreads widely as the fairway expands, the distribution is formed based on the center of the fairway, and assuming a normal distribution, the grounding probability may increase to a certain extent, depending on the deviation. Since the evaluation of the grounding probability in this study is based on actual data, the track distribution according to the fairway expansion, the ship navigation deviation, and the estimate of the grounding probability will be left for future research. In this chapter, for fairways with high collision risk as observed using the ES model, such as the Yeosu fairway, Masan fairway, and Gadeok fairway, the fairway was extended to the safe water area between the fairway and obstacles, and the risk was re-evaluated to examine any changes. As the Yeosu Passage has an anchorage and a low-depth section on the right, and as there is a free water area on the left, the fairway was expanded and reset by approximately 1 km to the left. The Masan Passage was extended by approximately 300 m to Jiri Island, which is located above the North Passage, and based on Jamdo in the middle of the Passage, the North Passage was extended by approximately 400 m, the West Passage by approximately 500 m, and the South Passage by approximately 300 m. The Gadeokdo Island expanded the fairway by approximately 100 m in the direction of Gadeokdo on the right and approximately 300 m up to the obstacle on the left. Based on the ES Model in Ch. 4.2, the amount of risk change before and after fairway expansion was  
Figure 10: (**a**) Grounding frequency estimation results for the Wando fairway, (**b**) the Yeosu fairway, (**c**) the Masan fairway, and (**d**) the Gadeok fairway. analyzed. Figure 11 shows the current situation before the expansion of the fairway and the change in the ES value after the expansion. Figure 11: _Cont._  
In all three fairways, the ES Value decreased when the fairways were expanded overall. As for the characteristics of \(ES_{L}\) and \(ES_{S}\), \(ES_{L}\) increased and \(ES_{S}\) decreased as the vessel speed increased. If we consider whether \(ES_{A}\), which is a comprehensive environmental stress, follows the trend of \(ES_{S}\) or \(ES_{L}\) as the ship speed increases, it can be seen whether the fairway has a large influence on the vessel traffic volume, or whether the characteristics of the fairway affect the ship safety. In the case of the Figure 11a Yeosu fairway and Figure 11c Gadeok fairway, the \(ES_{A}\) value was found to be greatly affected by the vessel traffic volume, as the ES value decreased as the vessel speed increased. In particular, in the case of the Gadeok fairway, the ES value of \(ES_{A}\) decreased overall; however, the shape of the \(ES_{A}\) graph was similar to that of the \(ES_{S}\), indicating that the amount of traffic of the vessel had a great influence on the results. In contrast, in the case of the Masan fairway in Figure 11b, the ES value of the \(ES_{A}\) increased as the ship speed increased in the current state, and the fairway was found to be significant affected by the fairway characteristics.