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

Abstract

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.

Glossary

AIS

Automatic Identification System. A ship-borne transponder broadcasting information about the ship, the voyage and several other safety related issues.

Collision

An event type that occurs when a ship is struck by another ship.

Drift grounding

An event type that occurs when a ship loses its ability to navigate, through loss of steering or propulsion, and is blown onto the shoreline before it is either taken in tow or is repaired.

DWT

Dead weight tonnage

Event frequency

The number of events, such as inter-ship collisions, that occur per year at a specified location or within a defined area.

GT

Gross tonnage

IMO

International Maritime Organization

MARCS

Marine Accident Risk Calculation System. An accident and risk simulation programme developed by DNV Technica.

NCA

The Norwegian Coastal Administration

NM

Nautical mile = 1.852 km

Powered grounding

An event type that occurs when a tanker collides with the shoreline whilst underway.

Risk

The frequency of a hazard multiplied by its consequence. The term is, however, often used as the mere probability of an accident/incident with adverse consequences.

SOLAS

International Convention for the Safety of Life at Sea

Structural failure

An event type that occurs when a ship sinks in heavy weather or loses its structural integrity due to mechanical failure.