Taking on the challenge of risk assessment at sea


How does one predict an incident that occurs once every 5,000 years and more importantly, how can these predic- tions be validated?


Estimating the probability of collisions be- tween ships or of a contact with an offshore wind turbine can be a difficult task, given a certain sea area with all its characteristics and shipping routes. Over the last 30 years MARIN has developed the risk assessment tool, Safety Assessment Model for Shipping and Offshore on the North Sea (SAMSON), to tackle this issue. The traffic database is at the core of the risk assessment model. This consists of a route structure where the number of ships per year, (divided over 36 ship-types and eight ship sizes), are laterally distributed on the routes. Information has always been available about the number of ships sailing between various ports but not on the exact routes taken. This, however, is essential information.


Yvonne Koldenhof y.koldenhof@marin.nl


AIS data During the model’s initial devel- opment the sailing routes were established using experts, masters and pilots. Later on,


2006 20


Research for Emma Mærsk, largest container ship ever built


recorded data from observed ships during hundreds of aerial observation flights was used for validation. Nowadays, recorded AIS data is used to validate and establish the traffic pattern, the composition of the traffic and its lateral distribution. Both validations showed that the route structure established by the experts corresponded well with the routes followed in reality. The figure shows the route structure (red lines) and the AIS positions during one week at 10-minute intervals.


So over the years the essential input for the risk assessment - the traffic database - has been validated and updated. This has led to increased trust in the database and im- proved results. AIS also gives us information about the behaviour of ships and will be used to validate other parts of the model, such as the predicted number of encounters between ships.


2007


MARIN 75th anniversary ‘Future Waves’


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