Mapping the Knowledge Structure and Research Evolution of Urban Rail Transit Safety Studies

To better grasp the status quo of urban rail transit (URT) safety research and explore the knowledge base and hotspot trends, 1249 URT safety research papers from 1983-2018 were collected from the SCIE and SSCI databases of the WOS search platform as data samples. Co-occurrence analysis, burst analysis of keywords and co-citation analysis were adopted to analyze the current research situation of URT safety in the world by means of information visualization. The study found that risk analysis in the construction/operational phase, methods for predicting ground movements, and cause analyses of tunnel deformation and settlement are the knowledge bases in the field of URT safety research. Tunneling and Underground Space Technology, Safety Science, Atmospheric Environment, Lancet and Transportation Research Record are the core journals in the field. At present, the basic theory and research system of URT safety have been basically completed, but the research directions are too concentrated, and the frontier branches are too few. The research themes of URT safety were roughly grouped into three core paths: the "health risk" path, the "risk analysis - safety management" path and the "tunnel displacement/deformation" path. In the process of research and evolution, the research paths are refined step-by-step, and the research directions are transformed from macro to micro. The emergency evacuation of personnel in subway stations, the effects of particulate matter in subway air on human health and the use of computer technology for engineering optimization are the current frontiers of URT safety. URT safety research also tends toward risk analysis in the operational phase.