A New Risk-Based Early-Warning Method for Ship Collision Avoidance

The ship collision accident (SCA) risk for any ship approaching any other change from the causation probability (CP) to the geometric probability (GP) in regime. Because ship operators may not be aware of the environmental factors (EFs) related potential risks in high CP during the initial stage of the GP analysis process, it is likely that higher-grade SCA measures will not be taken. However, if any EF-related CP is told to ship operators, they can take more effective and intentional measures in time; moreover, if the CP corresponding to navigation-related EFs is no less than the risk early warning critical value (REWCV) calculated based on historical SCA data, SCAs will be in a high-risk level. A new method was put forward here based on a quantitative analysis of EFs and previous SCA statistics to provide early warning of any SCA risk. On this basis, a REWCV is obtained based on quantified EFs by means of such method which is relatively simple but high operational and practical. A case study of Three Gorges Reservoir in China indicates that the range of EF values whose probability of a SCA grows rapidly is consistent with environmental limits defined by Chinese maritime standards. Moreover, the modified critical value of the EF-related CP shall be further refined to act as the REWCV for CAs. In addition, the relationship (REWCV vs. the number of previous SCAs) was clarified.