Towards Sustainable Campus Mobility: Optimal Transition Planning for Battery Electric Bus Fleets

The electrification of public transport fleets is a critical pathway toward achieving national sustainability and emission reduction goals. This study develops a practical optimisation framework to guide the economic and operational transition of university bus fleets from diesel to battery-electric buses (BEBs). The proposed University Bus Transition (UBT) model is formulated as a multi-period integer linear optimisation problem that minimises the total discounted cost (TDC), including vehicle acquisition, battery replacement, charging infrastructure, maintenance, energy, and labour, subject to annual budget and service constraints. The model is applied to the King Fahd University of Petroleum and Minerals (KFUPM) campus to identify the optimal replacement schedule and fleet composition over a 20-year planning horizon. Results show that with a $400,000 annual budget and 50% electrification target, the total discounted cost of UBT model is $12.35 million. Feasibility analysis indicates that the upper electrification limit under the given budget is approximately 60%, beyond which the transition becomes economically infeasible. The findings highlight the financial and operational trade-offs involved in achieving sustainable campus mobility. Although based on KFUPM-specific data, the framework is adaptable to other institutional or regional transport systems with appropriate parameterisation. Future work should incorporate renewable energy integration, real-world charging patterns, and life-cycle emissions analysis to enable a comprehensive evaluation of electrified transport strategies.