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

近年来由于拥挤水域海岸带利用的发展而导致的通航水域的减少和游船的增加，给船舶交通带来了更大的危险。在这种情况下，多重相遇，即三艘以上船舶同时相遇的情况，被认为是导致碰撞的相当危险的情况，因为没有解决这种情况的航行规则存在。本研究旨在从海上交通工程的角度，减少船舶多次相遇的发生。本文提出的寻找减少多碰事件发生的有效对策的流程，从收集相关交通和网络数据入手，涉及到以下模型和技术：(1)掌握多碰事件发生现状的技术；(2)预测改变后网络上船舶时距和航向未来分布的仿真模型。(3)建立了计算网络变化条件下多次相遇概率的数学模型；(4)建立了船舶交通控制的仿真模型，为解决多次相遇问题提供了有用的信息。通过模型的开发和检验，我们发现了一些有趣的知识，包括：(1)导航网络中链路的统一和分散都会增加多次相遇的发生概率。这种趋势表明导航网络存在最优链路密度。(2)经常发生多次遭遇的水域取决于避碰中有无规则冲突等多次遭遇的类型。将上述模型和技术整理成“通过网络设计和交通控制减少船舶多次相遇的系统程序”。

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".