Influence of impact scenario models on collision risk analysis

An important element in assessing the consequences in a tanker collision is the probability of breaching an oil cargo tank. It is well recognized that the dynamic parameters at the moment of impact significantly affect the deformation energy. Assumptions regarding dynamic parameters at the moment of impact are nevertheless little discussed in context of collision risk analysis.The available impact scenario models are analyzed using a system risk approach. Comparison of impact scenario models from literature is performed with a risk analysis algorithm emphasizing on oil tanker collisions. Monte Carlo simulation is applied in the risk analysis algorithm for each impact scenario model. Only the impact scenario module is changed while other modules of the algorithm (encounter scenario generation, determination of deformation energy and structural hull capacity) are kept the same.Analysis reveals important differences in results of risk analysis when performed with different assumptions for the impact scenario. Moreover, in the discussion inherent conceptual limitations of the impact scenario models in the system risk framework are revealed. It is concluded that using more accurate collision energy and/or structural capacity models for purposes of maritime traffic risk analysis is currently not worthwhile, as the uncertainty regarding impact scenario is overwhelming.

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► Impact scenario models for ship collision risk analysis are put in a system risk framework.
► System risk framework shows logical fallacies in impact scenario models.
► A case study of tanker collision risk analysis is performed for various impact scenario models.
► Case study results show significant discrepancies between impact scenario model results for probability of tank breach.