## 7 Conclusions  
In marine traffic with complicated routes, implementing a TSS with precautionary areas alone may not fully address navigational risks, as demonstrated in this study, leaving room for improvement. Enhancing these precautionary areas into circular roundabouts can improve the overall navigation safety. The following conclusions were drawn:  
1. An important finding of this study is the prevalent non-compliance of domestic ferries with precautionary area guidelines in the Lombok Strait. This highlights the urgent need for targeted measures, such as stricter enforcement of TSS regulations, enhanced operator training, and potential modifications to the layout of precautionary areas, to better align with the operational realities of domestic ferries;
2. This study demonstrates how critical parameters, such as entry capacities, critical gaps, and follow-up times, can be implemented to improve the flow of marine traffic, drawing on best practices and formulas from road transport. The case study in the Lombok Strait TSS, which is also a \"chokepoint\", shows that circular roundabouts facilitate more seamless traffic movement, reduce navigational conflicts, and provide safer navigation compared to that of conventional layouts;
3. Critical gap determination using the ship domain approach was found to be adequate and can be implemented in the formula. In addition, using this approach, the overall safety of the ship can be reviewed from the perspective of the interaction among ships, both in the forward and sideline relations, and conflict between ships;
4. A comparison of the before and after modification of the precautionary area showed that the roundabout design effectively reduced navigational risks. These findings provide a framework for maritime authorities to redesign or enhance TSS management to increase navigation efficiency and safety.  
The proposed roundabout design represents a significant step forward in maritime traffic management. By integrating principles from road transport engineering, this study not only addresses localized navigational challenges in the Lombok Strait but also establishes a scalable framework for other high-density marine environments globally. These findings contribute to the evolution of international standards, offering maritime authorities a practical tool to enhance traffic efficiency and safety at critical chokepoints. As global trade continues to grow, adopting innovative designs, such as roundabouts, could play a pivotal role in shaping sustainable and efficient maritime transport systems worldwide.  
Conceptualization, D.K., Y.P., G.C., A.A.P., and J.R.K.B.; methodology, D.K., Y.P., and J.R.K.B.; validation, J.R.K.B., D.K., and Y.P.; writing--original draft preparation, D.K., Y.P., G.C., A.A.P., and J.R.K.B.; writing--review and editing, D.K., Y.P., G.C., A.A.P., and J.R.K.B.; visualization, J.R.K.B., and G.C.; supervision, D.K. All authors have read and agreed to the published version of the manuscript.  
This research was a part of a project titled \"Development of Smart Port-Autonomous Ships Linkage Technology [grant number 2520000126]\", funded by the Ministry of Oceans and Fisheries, Korea.  
Not applicable.  
The data presented in this study are available from the first author upon request.  
The authors declare no conflicts of interest.