Oil spill risk analysis of routeing heavy ship traffic in Norwegian waters

Norwegian authorities have for a long time been concerned about the risk of oil spills outside the Norwegian coast. One of the key measures adopted has been to reduce the risk of ship accidents by imposing sailing routes for heavy ship traffic (over 5,000 gross tonnages) with high environmental risk potential farther away from part of the coast. This article is based upon two reports which conducted risk assessments of imposing such sailing routes outside the entire Norwegian coast. These routes were proposed by an expert group consisting of relevant stakeholders. Data of traffic pattern and number of sailing were collected for the year 2008 using the universal Automatic Identification System (AIS). The proposed route was compared with 2008 traffic pattern in regard to the accident frequencies and the expected oil spills per year. An accident and oil spilling simulation program called MARCS was used to simulate these results. After conducting a traffic forecast for the year 2025, the simulation was again run and the results compared with the year 2008. In total, the proposed route is expected to reduce oil spills by 590 t per year in 2008 and by 3670 t in 2025. The main reason for this substantial reduction is that the number of groundings is reduced because of the distance from the shore being increased. The reduction was particularly strong for tankers.