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The Itaewon tragedy in South Korea highlighted the severe risks associated with ultra-high-density pedestrian environments. In this study, pedestrian safety in narrow urban alleys was quantitatively evaluated using a FLEXSIM-based Multi-Agent System (MAS) simulation that models individual pedestrian interactions under extremely crowded conditions. Two simulation scenarios were established: a typical alley configuration and a bottleneck condition caused by illegal construction. In addition, three pedestrian control strategies (i.e., bidirectional flow, right-side walking enforcement, and one-way traffic control) were comparatively analyzed. Evacuation time, pedestrian collision frequency, and associated risk levels (Level 0–Level 4) were evaluated according to pedestrian density and movement direction. The simulation results show that bottleneck conditions significantly increase pedestrian collision frequency and evacuation time under high-density conditions. Among the examined strategies, one-way traffic control most effectively reduced pedestrian interactions and evacuation delays, whereas the bottleneck scenario under bidirectional pedestrian flow showed the highest risk level. These findings highlight the importance of pedestrian flow control and bottleneck management in reducing crowd risk in ultra-high-density pedestrian environments and provide quantitative data for pedestrian safety assessment and crowd management planning. Furthermore, the present study provides a quantitative simulation-based approach for analyzing pedestrian collision risk and evacuation safety under ultra-high-density bottleneck conditions in narrow urban alley environments.
Park et al. (Fri,) studied this question.