Analysis of cascading failure induced by load fluctuation and robust station capacity assignment for metros

In this paper, we analyze metro cascading failure induced by load fluctuation and present a robust station capacity assignment method. A cascading failure model is proposed by considering system initial balance state, load matching, and capacity-based load redistribution. Based on random walks, an initial failure model is proposed to simulate different load fluctuations that represent unrealistic passenger flows for failure analysis. We study the actual case of Nanjing metro. The results show that small station tolerance and larger load fluctuation can lead to global network failure easily. The phase transition between network functional state and global failure is abrupt and first order-like, which is sensitive to station tolerance and load fluctuation strength. The coupling effects of station capacity, station tolerance, and load fluctuation strength on the network robustness are investigated and the optimal model parameters for robust station capacity assignment are obtained.