OPTIMAL CHARGING INFRASTRUCTURE DESIGN FOR BATTERY ELECTRIC BUSES

Abstract

Public transit agencies across the United States are rapidly converting their bus fleets from diesel or hybrid powertrains to battery-electric propulsion systems. To realize the benefits of this transition while retaining acceptable quality of service and limiting capital costs, agencies must intelligently decide where to locate recharging infrastructure. To address this challenge, this research developed two mixed-integer linear programming models that optimize the tradeoff between upfront charging infrastructure costs and operational performance in the form of trip delays and recovery times. A discrete-event simulation model was also developed to accurately quantify queue delays at heavily used chargers and to better evaluate system performance under real-world variations in key parameters such as bus energy consumption per mile. The models were applied to a case study of South King County, Washington, where an electric bus deployment is planned in the near future. The results showed that the models are effective at identifying sensible locations and ensuring that buses can charge without incurring additional delays. Limitations of the current research are also summarized, with future improvements discussed.