An analysis of oil spills from vessel traffic accidents

In addition to the traditional activities such as fishing and transportation, a steady growth in world trade, recreation, and exploration of underwater resources has caused a rapid growth in vessel traffic for several decades. This has increased the potential risk of marine casualties involving loss of life and damage to vessels, cargo, navigational aids, and structures (e.g. bridges). Various Asian, European, and North American countries have enacted a wide array of safety measures to reduce the casualties. For instance, the US Coast Guard requires all incoming vessels to have a local pilot on board, have an officer on the bridge, and that the vessel operator should establish radio communications with the Coast Guard after getting on board. In addition, traffic separation lanes and convergence points have been established to improve traffic flow. Navigational aids assist the vessel operators by sensing oncoming traffic hazards such as bridges and shallow waters. The US Army Corp of Engineers keeps ship channels open by regularly dredging waterways that are used for commercial traffic. In many countries, offshore deep water ports similar to the loop in New Orleans, Louisiana, have been constructed to reduce traffic near shallow and congested ports. In spite of all these safety measures, accidents do happen. In this paper, we study the historic data related to the vessel accidents over a period of several years. In particular, we focus on the distribution of sizes of the oil spills that have occurred during these accidents. The sizes of the oil spills are ranked from largest to smallest. The regression analysis showed a strong linear relationship between the natural logarithm of size of casualty and the natural logarithm of its rank. The regression coefficients may indicate the ‘degree of damage’ in a particular year or for a specific geographic region under investigation. It could be argued that they could be used to assess an aggregated impact of the implemented safety measures.