Problems of vessel traffic organization in approach channels are solved by Vessel Traffic Management Services (VTMS). One essential task for VTMS is to ensure a required level of traffic safety. As often vessel traffic is intensive, attempts are made to optimize it. This author aims to find a relevant solution based on a mathematical model, in which vessel speeds at particular fairway sections are varied. The model belongs to the class of mixed integer linear programming. The branch-and-bound method has been adapted to the proposed solution of the problem. The results are shown in tables, while certain aspects of solutions are illustrated graphically.
The optimisation of vessel traffic in narrow channels is concerned with the optimisation of vessel passage times with the regulations in force being complied with. These types of problems are normally solved by classical methods of linear programming. However, the implementation of solutions thus obtained is practically hardly feasible. This is due to difficulties in observing exact times of vessel entries into the fairway, maintaining exactly the expected times of passage along particular fairway sections. Therefore, it becomes necessary to account for inaccurate vessel entry and times of passing particular sections. Consequently, an optimisation problem in this context naturally fits in the format of problems of linear programming with fuzzy coefficients. This approach enables a more flexible formulation of an optimisation problem. From the point of view of the solutions obtained, the interpretation of fuzzy inequalities in the system of constraints is of much importance. The article presents solutions to the vessel traffic optimisation problem with the use of various interpretations of fuzzy inequalities. The calculation results are shown. These refer to vessel traffic in the Szczecin-Swinoujscie fairway. The results have been interpreted and conclusions have been drawn. INTRODUCTION
In this paper, the considerations on the relations between the maritime navigation, its geographical and navigational environment and its safety system are presented. The most important issues of the ships' navivation, its environment and maritime navigation safety system are also discussed and the most important relations are shown.
The paper presents some results based on the research made in the VTS Gdańsk area. Conclusions from the experiments shows that errors in the presentation of ships course and speed on the VTS operator console may not allow to VTS operator to react in time to solve the gangerous situation.
This article presents practical application of the probabilistic-fuzzy method for assessment of the safety of a ship manoeuvring in fairways. The method, based on the probabilistic risk analysis and elements of fuzzy logic, allows to account for a situation of threatened safety and a situation when a navigator intuitively thinks that the safety of manoeuvring ship is threatened. The probability of grounding of a ship manoeuvring in a fairway bend was determined. Then, with the use of experts’ knowledge and tools of fuzzy logic the probability of a dangerous situation was determined. Two different approaches, discussed in Part 1, have been applied for the determination of the probability. The results were compared.
The paper presents theoretical basis of the probabilistic-fuzzy method for assessing the safety of a ship manoeuvring on fairways. The method allows to account for such different states / conditions as the danger to the safety and the intuition that the safety of a ship manoeuvre is threatened, based on the probabilistic analysis of risk and elements of fuzzy logic. A dangerous navigational situation is defined as a fuzzy event. Two methods of determining the probability of a fuzzy event occurrence are presented. The results are compared with those obtained from a quantitative method of safety assessment based on probabilistic methods.
The paper presents the method of estimation of safety navigation. The proper criteria, measures and rate will need the estimation of safety navigation. These are very often expressed by risk. Four different definitions are used. The mostly used definition is a combination of accident probability with connection to its results. Probability of accident can be expressed in different manner. Three kinds of them are presented. Also the consequences of accident may be calculated in many aspects. There are necessary activities leading to efforts of unifying of these quantities.
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