Electric bus system design considering power grid disruptions

Transit operators worldwide are transitioning to electric buses to mitigate greenhouse gas emissions. This presents new challenges for operators and policymakers, as electric buses rely on electricity, thereby increasing the importance of a city's power grid infrastructure. Any power grid failure can potentially disrupt the advertised schedule of the electric bus service, leading to unmet passenger demand. This study proposes a two-step methodology for designing an electric bus system that considers the relationship between a city's power grid and its electric bus system. The proposed framework is formulated as a Mixed Integer Linear Program (MILP) and attempts to minimize the worst-case trip losses in the network with the possibility of spatial failure of power grid substations in a city. The framework is then applied to the bus and power grid network of Delhi, India. Due to the complexity induced by a large number of binary variables present in the formulation, local branching is utilized to solve the problem efficiently. Results indicate that the proposed methodology can reduce the potential trip loss in the network by 30 % with marginal additional costs from a cost-optimal electric bus system. Moreover, case study analyses lead to policy recommendations for reliable electric bus system designs, demonstrating the need of a departure from typical cost-optimal design.