Evaluation of ship navigation safety in bridge group water based on extension cloud

In response to randomness and fuzziness issues of ship navigation safety evaluation indicators in bridge group water, extension cloud model is applied to evaluation of ship navigation safety in bridge group water which has been providing decision support for improving ship navigation safety, and transformation between qualitative indicators and quantitative indicators is achieved. Firstly, 10 indicators are selected from natural environment, waterway environment, and traffic conditions to establish evaluation indicator system for ship navigation safety in bridge group water. Secondly, Analytic Hierarchy Process (AHP) is used to determine the weights of each indicator. Finally, evaluation model for ship navigation safety in bridge group water based on extension cloud is constructed to analyze the safety status of ship navigation in bridge group water area at the exit of Dongting Lake and determine safety level. The results show that evaluation level of ship traffic flow is higher, the evaluation level of bridge layout and safety facilities is high, the evaluation level of wind and flow is average, and the evaluation level of other indicators is low. Countermeasures and suggestions are proposed for these indicators. The feasibility and applicability of the extension cloud model in evaluation of ship navigation safety in bridge group water are demonstrated through case analysis.