ABSTRACT
To prevent ship traffic incidents in the Japanese coastal sea, the Japan Coast Guard has implemented new traffic rules: a recommended route off the western coast of Izu O Shima Island and a designated shipping route at the entrance of Tokyo Bay. Four years after the implementation of the rules, ship traffic behavior in these areas was considered stable. Extensive studies have been conducted to improve the safety of these waters. In this paper, we report a follow-up study related to the aforementioned shipping routes from the following viewpoints: (i) ship traffic behavior, focusing on the number of ships that comply with the rules, and (ii) traffic safety, assessed using the encounter frequency method and the obstacle zone by target method. It was found that two shipping routes in close proximity interacted which resulted in an increase in the ship compliance rate more than that of a single route. In addition, these measures helped in mitigation of the collision likelihood not only in the water around them but also in the water between them.
