Relationship between Unsafe Ship-handling Situation and Marine Accidents at the Kurushima Strait

Abstract

An Unsafe Ship-Handling Situation (US) is known as an index that is able to estimate of a potential risk of a marine accident. It is based on the principle of Heinrich, according to this principle, an US corresponds to the detection of some several thousand hidden unsafe situations behind one obvious case of an accident. An US can be determined, in each time section, in terms of whether or not the Time To Collision (TTC) exceeds the Short Stopping Time (SST) under the corresponding speed. The TTC is calculated as the time until the ship makes contact with the obstacle on the predicted path of ship. In this study, it has studied from viewpoint of occurrence position of an US and marine accidents at a narrow channel, Kurushima Strait. We researched relationship between collision positions of prediction wakes and an occurrence position of marine accidents. And we defined to Emergency Level (EL) that can express affordability of avoidance of serious situations and we attempted to weight to an US frequency by EL. As a result, it is able to estimate high frequency marine accidents area from occurrence positions of an US. And it will help to determine maintenance or improvement area.