Title: Simulation of conflict risk for marine traffic within a seaport
Abstract: With steady growth of the shipping industry over the past decade, the world's busiest ports are faced with traffic congestion and potential risk of traffic incidents/accidents in port waters.The causes of traffic incident/accident and traffic congestion come down to a central issue: traffic conflict.Traffic conflicts are prone to occur in port waters due to the special characteristics of port traffic in limited sea space, high traffic density, and complex operational regulations.A conflict is an undesirable event related to safety concerns as well as congestion and delay which affect the efficiency of port operations.Maritime control centers often play an advisory role, which cannot satisfy the demand on traffic management arising within a busy seaport.Conflict resolution is a critical issue in marine traffic safety, and of great practical significance in traffic congestion management.However, there is no positive control as to systematically resolve conflicts in an effective manner.This research aims to suggest and provide measures to resolve conflicts for planning and scheduling of port operators so as to minimize delay and congestion ahead of time (for example, in the next day).Two aspects are considered in conflict resolution.Safe navigation of vessels without conflicts is taken as the first priority.The other issue is concerned with reducing the impact of conflicts through minimizing total delay in the traffic network.Systematic strategy for conflict resolution is a two-stage process.The first stage is referred to as vessel rescheduling for eliminating potential conflicts under original schedules of vessels.An original conflict-free scheduling algorithm is developed in this study for coordinating vessels without conflicts for a given schedule.The second stage is a simulation of vessel movements as a result of the stochastic fluctuations in vessel speed and deviations in timetables in real-time.The applicable corrective measures are identified by a decision-making mechanism.These measures conclude general rules or guidance for navigator chooses proper evasive maneuvers.Conflict detection as the basis of conflict resolution is the other key objective of this research.Ship domain can be referred to as the clearance area around a vessel, with which the vessel can keep sufficient distance to avoid a conflict with other vessels.An algorithm is presented to predict a potential conflict through an evaluation of positional relation of two vessels' domains before they actually encounter each other.