Modelling bus-based substitution capabilities for metro systems using bipartite graphs

A disruption of metro services can have a negative impact in the performance of a city's transportation system and hinder mobility needs of travellers. Investigating the vulnerability of metro systems is required for planning mitigation actions, such as bus substitution services. This study develops a model, which consists of a bipartite graph and its projection to represent the bus substitution capabilities for metro networks. The proposed methodology effectively identifies significant substitution elements (bus lines), evaluates the robustness of alternative options in terms of both connectedness and connectivity, and suggests effective strategies for enhancing bus line capacity to improve network robustness. By applying the methodology to a real-world metro network, valuable insights are gained regarding important bus lines and substitution robustness. Study findings suggest that approaches based on the weighted degree exhibit the greatest effectiveness when it comes to connectivity and the overall efficiency of the network. These findings can assist public transport operators in proactively managing disruptions and improving their services.