The bus system in Seoul operates across approximately 437 routes with 7,393 buses, playing a crucial role in the city’s transportation network. As of 2019, before the pandemic, it accounted for approximately 24% of the travel mode share and was utilized by about 7.7 million people daily. However, several practical limitations have led to issues with the city’s arterial (blue) bus lines, such as unclear roles due to the operation over long distances between short bus stops, the necessity of operating numerous vehicles on long routes, and leading to driver fatigue. The following issues have been identified as significant concerns.
This study aims to assess the effectiveness of Seoul’s arterial bus route network, which currently needs a more apparent hierarchical structure. The first goal is to identify evaluation criteria for determining whether the bus routes are organized efficiently. The study will derive optimal directions for Seoul’s arterial bus routes based on these criteria. The study will establish ‘ideal’ benchmarks through optimization techniques based on the identified evaluation standards for evaluation and analysis. It will then compare these ideal routes with the current ones to understand the differences and determine how the arterial bus network can be operated more efficiently.
In this study, evaluation criteria were developed through a three-round Delphi survey conducted with transportation experts. The survey results revealed that the essential conditions for main bus routes include low curvature, high productivity, low congestion rates, and short transfer waiting times. Additionally, there is a fundamental need for adequate coverage in response to demand. The optimization process utilized the identified indicators as objectives, and a genetic algorithm compared the current routes to the optimized ones.
The optimized routes, when compared to the current ones, exhibited greater distances between stops and relatively shorter overall route lengths. Specifically, the optimized versions demonstrated a reduction in total length for long-distance routes compared to the existing routes. Furthermore, the optimized network showed improvements in efficiency with more effective paths, contributing to the network’s robustness and providing users with a greater variety of choices. The current and optimized arterial bus routes maintained similar interregional connectivity, preserving essential travel links between areas.
The conclusions that can be drawn from this study are as follows: First, the roles of arterial bus lines as distinct from branch bus lines need to be clearly defined. Second, various operational forms, such as express services for routes passing through the same hubs, must be implemented. Third, the primary functions of the arterial bus lines must be enhanced. Lastly, minimizing long-distance routes is essential. If these policies for arterial bus operation are established, more effective arterial bus operations could be achieved.