# Multi-Objective Routing and Categorization of Urban Network Segments for Cyclists
## 4 Discussion
### General Discussion--Observations
Solution 3 is well suited for cyclists who prioritize both safety and comfort, as it minimizes interaction with fast-moving vehicles and provides wider pavements. This makes it attractive to recreational cyclists who may be more cautious, as well as to commuters who prefer a safer route during periods of low light, such as early mornings or late evenings. This route's design also considers safety factors that could appeal to cyclists traveling during off-peak hours when traffic speed and volume may be higher. In contrast, solution 4, with its focus on minimizing both slope and interactions with bus traffic, offers a smooth, steady cycling experience. Recreational cyclists may particularly benefit from this option during midday or weekend trips when bus traffic may still be present but less intense compared to peak hours. Additionally, commuters who wish to avoid frequent contact with buses and other large vehicles may find this route favorable during busier travel times, as it offers a less obstructed pathway through the urban environment, thereby enhancing the safety and comfort of the ride. It should be noted that since the routes of these solutions are dominated by links within the Zappeion Gardens, this difference in pavement use is mainly found on Amalias Avenue whereas in solutions 1 and 2 the route from Zappeion to Syntagma is via the road, while in solutions 3 and 4, it is via the pavement. These four solutions also differ in the choice of cyclists at the start of the route, whereas in solution 1 they proceed from node 1 directly to node 82 (like vehicles), while in solutions 2 and 3 that maximizes the pavement width and overtake ability, they choose to move from the crossing first to node 81 by proceeding on the pavement after crossing to node 82. In solution 4, which maximizes the bus transit variable, they move from the start on the south pavement on Vasileos Konstantinou Avenue, thus avoiding contact with the bus completely, as shown in Figure 11.  
In this study, Pareto optimality served as a crucial evaluation criterion for comparing alternative cycling routes generated by the NSGA-II algorithm. A solution was deemed Pareto optimal if no other solution could improve one objective (e.g., minimizing travel time) without worsening at least one other (e.g., increasing safety risks or discomfort) [43]. The key criteria used to assess Pareto optimality included travel time, safety (measured through factors like average vehicle speed and contraflow occurrences), comfort (through pavement width and bus transit interactions), and slope. By constructing a Pareto front of non-dominated solutions, we identified a subset of routes that represented the best trade-offs among these competing objectives, allowing for a balanced approach in route selection based on different cyclists' needs. This method ensured that each route on the Pareto front could cater to varying preferences, from speed-focused commuters to safety-oriented recreational cyclists. Through this approach, we enabled a comparison of routes that align with specific goals without compromising on essential aspects like safety and comfort. The implementation highlights the algorithm's capability to provide solutions  
Figure 11: Solution variations in the route initiation on Vasileos Konstantinou Avenue, where red: Road Particle; orange: Pedestrian Particle; yellow: node. Source: Open Street Maps. with minor variations, effectively capturing the specific needs of commuter cyclists and recreational riders across different scenarios.