Network Design and Traffic Control for Reducing the Probability of Multiple Encounter of Ships

随着海岸带开发利用的进展，在拥挤的沃茨中，航行沃茨的减少和游船的增加都给船舶交通带来了更大的危险。在这种情况下，多船会遇，即三艘以上船舶同时相遇的情况，由于没有解决这种情况的航行规则，因此被认为是一种非常危险的导致碰撞的情况，本研究旨在从海上交通工程的角度减少多船会遇的发生。本文从收集交通和网络数据入手，提出了减少多遇事件发生的有效对策，包括以下模型和技术：（1）掌握多遇事件发生现状的技术;（2）估计改变后网络上船舶的车头时距和航向未来分布的仿真模型。(3)a通过对模型的建立和检验，发现了一些有趣的知识：（1）航线网络的统一和分散都增加了船舶多遇的概率;（2）航线网络的分散和统一都增加了船舶多遇的概率;这种趋势表明存在最佳链接密度的导航网络。（2）多船会遇发生的水域取决于多船会遇的类型，如有规则冲突和无规则冲突的避碰，将上述模型和技术整理成“通过网络设计和交通控制减少多船会遇的系统程序”。

Both the decrease of navigational waters and the increase of pleasure boats which derive from the recent progress of coastal zone utilization in congested waters carry more dangerous situation in ship traffic. Under such a situation, a multiple encounter, the situation that more than three ships simultaneously encounter in each other, is focused as a quite dangerous situation leading to a collision, because no navigational rule to resolve the situation exists.This study aims to reduce the occurrence of multiple encounter of ships from a view point of maritime traffic engineering. The proposed procedure to find effective counter measures to reduce the occurrence of multiple encounters starts from collecting traffic and network data concerned, and involves following models and techniques :(1)a technique to grasp the present situation of occurrence of multiple encounters,(2)a simulation model to estimate the future distributions of headway and sailing course of ships on the network after changed.(3)a mathematical model to calculate the probability of occurrence of multiple encounters under the changed network,(4)a simulation model which gives us useful information on ship traffic control to resolve multiple encounters.Through the model development and its examination, some interesting knowledges have been found, which include :(1)Both unifying and dispersing links of a navigation network gives the increase of the probability of occurrence of multiple encounter. This tendency suggests the existence of optimal link density of a navigation network.(2)The water area where multiple encounter often occurs depends the types of multiple encounter such as those with and without rule conflict in collision avoidance.The models and techniques mentioned above are arranged into "A systematic procedure to reduce multiple encounters of ships by network design and traffic control".