Optimal additional evacuation route analysis in deep underground station structures using Dijkstra's algorithm

This study examines the optimal additional pathways to reduce the maximum evacuation time using Dijkstra’s algorithm, targeting a deep underground station structure in Seoul. The reduction rates in the maximum evacuation time were evaluated across seven cases, including baseline scenarios without additional pathways. Pedestrian speed was adjusted by applying a crowd density-based reduction factor. The maximum evacuation time was 590 s without the additional pathways and 369 s when additional pathways were implemented on floors B2 and B1, representing a 37.5% reduction. The most significant reduction occurred when pathways were simultaneously added on B6 and B1, as well as B2 and B1, resulting in a maximum evacuation time of 340 s, a 42.4% decrease compared with the baseline scenario. These findings underscore the importance of constructing additional pathways to ensure occupants can evacuate within the 6-min golden time specified by the Korean Ministry of Land, Infrastructure, and Transport. • This study identifies optimal evacuation routes in a deep subway station under disaster scenarios. • Additional pathways reduced the maximum evacuation time by 42.4%, meeting the 6-minute standard. • Congestion alleviation rate was proportional to the reduction in maximum evacuation time. • Mitigating congestion in evacuation-vulnerable zones, which have the highest crowd density, can effectively reduce the maximum evacuation time. • Utilizing this zone to alleviate congestion in future studies or designs can enhance subway safety.