# Application of Collision Warning Algorithm Alarm in Fishing Vessel's Waterway
## 4 Application in Fishing Vessel's Waterway Based on Vpass Data
### Case Study of the Collision Warning Algorithm Application Based on Vpass Data
#### 4.2.1 Overview of the Maritime Risk Assessment Tools  
1. ES Model  
The ES model is a quantitative numerical model based on the scale of the burden that the operator feels difficulty in steering due to the surrounding environment (terrain, other ships, etc.) of the vessel by environmental stress (ES) value, which is the evaluation index [33]. The difficulty in steering was based on the case where conditions, such as natural, geographic, facility, and transportation restrict the behavior of the ship operator. The size of the load applied to the ship operator was considered, in addition to the behavioral restrictions. If the stress value is due to the steering environment, it is called the land of ES value (ESL), and if it is due to transportation environments, it is called the ship of ES value (ESS). The size of the load that combines these values is called the aggregation of ES value (ESA). The ESS value was used because this study assesses the risks among ships. To calculate the ES value, the risk concerning the relative distance between the ships in relation to collision (SJ) value must first be calculated; the calculation method is shown as Equations (3) and (4). \[\text{SJs}=\text{f}(\text{R}/\text{V}) \tag{3}\]  
\[\text{SJs}=\alpha\times(\text{R}/\text{Lm})+\beta \tag{4}\]  
where  
SJs: Risk concerning the relative distance between the ships in relation to collision;  
R: Relative distance between two ships;  
V: Relative speed of the two ships;  
Lm: Average length of the two ships;  
\(\alpha=0.00192\times\text{Lm}\)  
If crossed from starboard, \(\beta=-0.65\times\text{ln}\,Lm-2.07\). If crossed from portside, \(\beta=-0.65\times\text{ln}\,Lm-2.35\). If meeting from the stem, \(\beta=-0.65\times\text{ln}\,Lm-2.0\). If the own ship is overpassed from the stern, \(\beta=-0.65\times\text{ln}\,Lm-0.85\). The SJs value is calculated as a risk level from \(-3\) to \(+3\), and this is a value based on the subjective judgment of the navigator. The risk level of \(-3\) to \(+3\) by each course angle, which is calculated by each \(1^{\circ}\) of course angle, was converted into the scale of \(0\) and \(6\) where \(+3\) is \(0\) and \(-3\) is \(6\). The risk levels were summed up in the range of \(\pm 90^{\circ}\), and the value was set to ESS. Moreover, \(0\times 180=0\) was set as the minimum, and \(6\times 180=1000\) was set as the maximum. The SJs value corresponds to the ship operator's sense of risk, where \(3\)-\(0\) is not risky and risk, \(-1\) is somewhat risky, \(-2\) is risky, and \(-3\) is very risky. Thus, for a range between \(0\) and \(1000\), the load rank was categorized as negligible when the scope was between \(0\) and \(500\), marginal when the scope was between \(500\) and \(750\), critical when the scope was between \(750\) and \(900\), and catastrophe when the scope was between \(900\) and \(1000\). 2. IWRAP MkII  
IWRAP MkII is a useful modeling tool for waterway risk assessment because it estimates the frequency of ship collisions and stranding based on traffic volume, traffic distribution, and undersea geographic information [34]. Since this study assesses the risk of ship collisions, the focus is only on collisions. The conceptual theory for calculating the frequency of collision or stranding follows the principle formulated by [PERSON], as shown in Equation (5). \[\lambda\text{col}=\text{P}_{\text{C}}\times\text{N}_{\text{G}} \tag{5}\]  
where  
\(\text{N}_{\text{G}}\): : Geometric number of collision or grounding candidates;  
\(\text{P}_{\text{C}}\): : Causation factor. Collisions are mainly divided into two categories: those caused by the passage zone (head-on or overtaking collision) and those caused by two routes crossing or merging at the curve of the fairway (crossing collision). The equation for estimating the frequency of head-on or overtaking collision is given by Equation (6), and that of a crossing collision is given by Equation (7).