Effects of built environment in subway stations on pedestrian injuries

Objective: In South Korea, major events that cause many subway injuries due to trains or other facilities and force majeure such as terrorism or natural catastrophes have markedly decreased. However, there are still many other types of cases involving injury inside subway stations. To reduce this damage, it is essential to identify and evaluate the factors that have the potential to lead to event occurrence. In other transportation domains, such as in the area of road traffic, crash or collision frequencies have been estimated using a safety performance function (SPF) with explanatory variables that represent risk factors. We introduce an SPF modeling approach for the injury events inside subway stations to interpret the risks to the users moving between exit and platform for boarding and alighting and put forward implications for the operation and design of stations. Methods: We conducted SPF modeling based on a negative binomial regression analysis, using 4039 injury event datasets for eight lines and 235 stations in the Seoul Metropolitan Subway network. The number of passengers is an exposure variable, and other explanatory variables consist of spatial attributes inside stations. Results: The number of users of each station has a positive and nonlinear correlation with event frequency. Several spatial attributes have positive correlations with events, especially the vertical movement of passengers and the total length of escalators, and the number of wheelchair lifts and floors in each station. Results estimate that 54% more event occurrence in transfer stations than in non-transfer stations. The total length of platforms and the area of shops in each station, on the other hand, are negatively correlated with events. Conclusions: The results provide quantitative guidance for dealing with risk factors in each corresponding phase of the design, construction, operation, and maintenance of subway stations.