Risk evolution model of marine traffic via STPA method and MC simulation: A case of MASS along coastal setting

Abstract

Marine traffic safety for Maritime Autonomous Surface Ship (MASS)is affected by the maritime environment and complex human-machine technical systems, and it is necessary to reveal its risk evolution characteristics involving new technology. The novel risk evolution model based on the system-theoretic process analysis (STPA)method for specific scenarios is established to determine the risk mechanism in random processes. First, by combining Markov chain (MC) with cloud model based on the information transmission path, the Markov process hypothesis is proposed to devise a coupling effect model of system components and external interference environment. Second, operation and control modes for MASS under different scenarios based on STPA are constructed and analyzed, which are based on clarifications regarding two models for the parallel control of MASS. Third, a systemic risk model using safety control methodology is constructed considering the operation scenario of MASS. Last and not least, the risk performance in the MASS navigation process is simulated to reveal the emergence characteristics of ship navigation process risk after applying specific scenarios under three modes. Application examples show that the process risk emergence of MASS navigation is characterized by the dependence on safety information transmission path. Different transmission paths lead to inconsistent risk evolution results. The randomness and complexity of external environmental disturbances are the main factors involved in the formation of navigation risks in MASS.