Rethinking critical node problem for railway networks from the perspective of turn-back operation

Abstract Vulnerability assessment studies addressing the critical node problem for railway networks do not recognize the importance of turn-back operations as a typical reaction to disruption. The aim of this study is to explore the significance of turn-back operations during the process of identifying critical stations. This significance was quantified by comparing the results of critical stations (both with and without turn-back operations) in the Nagoya metro, Japan. The results indicate a large difference between critical stations identified with turn-back operations and those without. In addition, the criticality of stations without turn-backs tends to be underestimated. Our findings suggest that analysts and decision makers should rethink the critical node problem for railway networks from the perspective of turn-back operations.