## 6 Conclusions  
The MTSA regulations are regulatory in nature. Hence, when considering the application scope of these regulations, the system should be revised to consider the safety benefits of each option and account for the administrative and economic burden on the operators. The MTSA regulations often overlook coastal passenger ships less than 100 m long. In this study, the MTSA-related ARR--an important safety benefit factor for areas where coastal passenger ships less than 100 m long operate--was derived while taking into account the expansion and application of marine development projects. Using GIS technology, spatial information on marine structures and facilities that received MTSA over the past five years (2010-2014) was obtained. Subsequently, considering the marine development project cycle, the route information of coastal passenger ships collected in the last six years (2017-2022) after MTSA implementation was analyzed to classify the routes near marine structures and facilities into MTSA-related and MTSA-unrelated route information. The MTSA-unrelated route information was combined with the MTSA-related accident occurrence information to derive the original Data U set. However, the original Data U set had a relatively small number of accident occurrence data groups; therefore, SMOTE oversampling was applied to adjust the ratio of the data. Next, the random forest technique, which is an ML algorithm, was used to train the probability of MTSA-related accident occurrence by group using 80% of the SMOTE Data U set. Subsequently, the occurrence of MTSA-related accidents in an MTSA-unrelated operating environment was predicted based on the safety diagnosis of the project site's operating information in the 2022 MTSA-related route information. The annual number of operations was identified as the most important feature among the independent variables. The validation of the random forest algorithm model based on the SMOTE Data U set yielded an accuracy of 0.98. Finally, the annual average number of actual MTSA-related accidents that occurred over the past six years in the MTSA-related route information was applied to denote the expected number of MTSA-related accidents in the future. The predicted numbers of MTSA-related accidents in the MTSA-unrelated and MTSA-related operating environments (derived from the same MTSA-related route information) were both applicable to the accident reduction formula. By applying a correction coefficient of 0.80 for the model accuracy of the original Data U set, the MTSA-marine ARR was calculated to be 17.41%. The future application of the results of this study to safety benefit assessments could provide evidence for improving the MTSA system. In addition, the findings of this study can serve as a tool for identifying appropriate regulatory relaxation or improvements in similar regulatory frameworks. However, this study has the following limitations:  
First, this study was focused on expanding the limited scope of MTSA to coastal passenger ships and analyzing coastal passenger ship accidents. The scope of MTSA should be further expanded in the future by examining and analyzing the maritime routes and accidents of other vessel types. In particular, accidents involving dangerous cargo ships can lead to significant environmental damage. Hence, the scope of the MTSA regulations should be expanded regardless of the length and type of the vessel. Dangerous cargo ships frequently travel from ports near onshore oil-refining and petrochemical plants to their destinations; therefore, new methods for data collection and pre-processing may be necessary for other maritime routes. Second, the structural and motion characteristics of the operating ships were not reflected in the basic data. Coastal passenger ships are classified into various types, such as general passenger ships, high-speed crafts, and car-ferries. Their speeds and engine outputs differ, and these factors are significant in accident prediction.