The risk assessment and management of the Istanbul strait

Abstract

There are more than 260 straits in the world. But none of them even remotely resembles the Turkish Straits in terms of the geography and other factors as they are considered as one of the most strategic waterways of the world. The Turkish Straits comprising of the Istanbul Strait and the Çanakkale Strait, are the second highest congested international waterways (second only to the Malacca Strait), since they constitute the only waterway between the Black Sea and the Mediterranean Sea. Along with the sharp rise in the number of oil tankers and the amount of oil they carry, especially after the 1990’s, the increasing maritime traffic in the Turkish Straits brings about a continuously growing risk of a large-scale accident in the Straits leading to huge environmental and material damage, as well as loss of human life. Earlier unfortunate examples show that such risk may turn into a nightmare at any time, unless the necessary measures are taken to ensure safety of navigation in the Straits. Potential maritime accidents, which impose serious risks on the nearby population, environment and property, as well as cultural and historical treasures of Istanbul, are the subject of this study. The objective is to measure the risk associated with the various environmental, physical and technical conditions related with the “potential accidents” in the Strait, based on the past accident and transit traffic data, along with the subjective expert evaluations of the accidents’ consequences. In this context, the key factor is the likelihood of an accident, along with the consequences of this potential accident in the Strait. In this regard, the Istanbul Strait Risk Model consisting of three sub-models, namely econometric, probabilistic consequence and analytic hierarchy process (AHP) models, has been developed. In the framework of the development of the econometric model, logistic regression techniques are used based on the past accident statistics of 1995- 2004, along with the year 2005 accident free transit data. This model is extensively used for testing the effects of the factors such as visibility, precipitation, wind speed, pilot utilization, local traffic and vessel characteristics, which may affect the accident probability in the Strait along with the scenario analysis. In the second part of the study, based on the experts’ views, the realization of various consequences after an accident occurrence is estimated. This model also demonstrates the effects of factors, such as vessel type and its cargo status, vessel length and accident location, over the realization of any consequence. Finally the AHP model is deployed to present the effects of other factors that are not considered in the first and second phase models. The results of this study identify and, to a large degree, quantify the risks and their sources regarding the maritime traffic in the Strait. As such, it can be said that the obtained results can also be deployed in selecting and guiding the measure to be taken regarding the mitigation of these risks; and thus enhance the maritime safety in the Strait. Nevertheless, there is still room to improve the safety and to reduce the maritime risk stemming from the maritime accidents in the Istanbul Strait.