Risk analysis and modeling of the maritime traffic in the strait of Istanbul

Abstract

The Istanbul Strait connecting Marmara and Black Sea is one of the narrowest waterways in the world with daily crowded local and transit vessel traffic. Other features such as currents, wind, fog and sharp turns in that narrow waterway lead to a high accident risk for transiting vessels. The most common accidents in the Istanbul Strait are collisions and groundings which have caused considerable amount of deaths and sea pollution so far. The main aim of this study is to measure the collision and grounding probabilities in Istanbul Strait based on mathematical models. A simulation model is built that mimicks the transit traffic pattern of the Istanbul Strait for seven years through a developed scheduling algorithm. The algorithm decides the entering vessel type and entrance times each day regarding past data and established maritime rules and regulations. In order to estimate the collision and grounding probabilities, the geometric probabilities (the vessel being on a collision or grounding course) and the causation probabilities (given that the vessel on a collision or grounding course, the inability to prevent accident) are multiplied. The geometric probability is estimated based on a physical model whereas the causation probability is estimated through created Bayesian networks. Effects of some vessel based and external factors on collision or grounding causation probability are investigated. The results show that having pilot service dramatically decreases the causation probability of collision and grounding. The number of accidents are estimated by integrating the probabilities with the simulation model and the results are compared with the actual number of accidents. Effects of some factors (such as sectors, season, day light, transiting vessel direction and type) on number of collisions are also investigated. For number of groundings, the factor analysis is also elaborated on transit traffic density, as well. The results show that most frequently dry cargo vessels collide and ground in the Istanbul Strait. Number of collisions and groundings increases at nights in model results and actual cases. Moreover, as the transit traffic density increases, number of groundings increases as well.