## 2 Literature Review
### Roundabouts in Marine Traffic  
The practice of adhering to pre-established routes for passenger ships navigating the North Atlantic started in 1898 and was subsequently integrated into the International Convention for the Safety of Life at Sea. In 1961, navigation institutes in Germany, France, and the UK conducted research on strategies to mitigate collision hazards in the Strait of Dover and other high-risk zones. In the same year, the concept of \"Naviroutes\", which are protected navigable areas marked by blue lanes that separate opposing traffic streams, was introduced as an outcome of research in 1959 by Capitaine [PERSON] [PERSON] of the French Hydrographic Service in two articles on the marine traffic in the Strait of Dover, which introduced the concept of 'roundabout' cross-overs. Subsequently, [PERSON] incorporated circular crossovers at convergence points, functioning similarly to conventional roundabouts, and suggested that organizing traffic in such a manner would significantly reduce collision risks by providing clear guidelines for ship movement, particularly in areas with high traffic density, emphasizing the importance of structured and predictable traffic flows to enhance maritime safety [23]. Several studies and their suggestions were then presented to the IMCO (previous name of IMO), which oversees ship routes, ensuring maritime safety and preventing pollution. The fundamental principle of segregating opposing traffic was adopted and published in 1962. This has been implemented in several regions across the globe since [24; 25; 26]. In 1993, an attempt was made to further refine the roundabout model by developing a microscopic mathematical model to describe ship behavior when merging into a roundabout. This conflict-point approach treats the roundabout as a series of T-shaped intersections, with the model considering factors such as ship spacing distribution and critical gaps for merging. The results demonstrated that marine roundabouts can significantly improve traffic flow and safety in congested days by organizing traffic more effectively and reducing collision risk. Subsequently, the evaluation model was improved by incorporating the distribution of ship sizes, addressing the limitations of previous models that assumed a uniform ship size. This refined model provides a more realistic assessment of traffic safety and demonstrates that marine roundabouts can enhance traffic flow and reduce collision risks by ensuring safe merging distances [27; 28]. In 2003, a roundabout for marine traffic, adapting collision avoidance strategies from air traffic management, was introduced. The mathematical model divides the area around a ship into safety, action, and observation zones, allowing ships to navigate a circular route before resuming their original paths. Simulations demonstrated that this method effectively handles complex multiship encounters, ensuring that ships maintain safe distances and reduce the likelihood of collisions [29]. This approach was then expanded by investigating the impact of different maritime traffic schemes on vessel safety, with a particular focus on classical route crossings and roundabouts. Using a simulation model based on cellular automata, as previously conducted for road traffic, various scenarios of vessel priority and traffic flow parameters were analyzed. The findings indicated that well-organized traffic schemes such as roundabouts significantly reduce collision risks by maintaining safe distances between vessels and improving overall traffic safety management [30]. Following recent studies on road and marine transport, considering roundabout design and conversion, this study examines the best practices and formulas derived from road transport to redesign rectangular precautionary areas into circular roundabouts in maritime environments. The objective is to determine the capacities and overall performances of the proposed roundabout to enhance the overall traffic safety in the area, similar to their equivalents in road transport.