ABSTRACT
Route plans for ships have typically been designed based on weather and maritime meteorology information, focusing on navigating effectively by avoiding hazards in the natural environment and considering environmental conservation. By contrast, safety factors, such as avoiding dangerous ship encounters and reducing ship collision risks, have not been widely considered, despite the fact that collisions tend to occur in known locations, where the number of potential collisions is high. In this study, route-planning to reduce collision risk was investigated. A method for probabilistically estimating the total number of encounters occurring on routes was considered using mesh-based encounter frequency. Using this method, the total number of encounters were calculated for a route commonly navigated by ships and for two routes which have been altered to avoid areas with high encounter frequency. The calculation results showed that small changes in routes could reduce encounter frequency. Additionally, the results of encounter frequency compared with those of Obstacle Zone by Target (OZT), and similar trends were observed.
