Evaluating multidimensional fairness in shared micromobility: Case studies of docked and dockless systems

Shared Micromobility Systems (SMS) have become a key component of urban transportation. While they offer flexible and sustainable mobility options, growing concerns have emerged about the society-wide equity impacts from these services. As SMS are shaped by intertwined decisions from policymakers, operators, and users, fairness in these systems is multidimensional: it spans static design choices and dynamic operation patterns, and can be evaluated under horizontal equity, vertical equity, or combined fairness-efficiency principles. In this study, we develop a modeling framework that links decisions to stakeholder utilities, characterizing SMS-related benefits, and then to fairness metrics. Utilities are distinguished into static decision outcomes, capturing capacity, safety, and accessibility, and dynamic system outcomes, capturing availability, usage, and idle time. We apply the framework to evaluate census tract level fairness in a docked bike sharing system (Citi Bike) in New York City and a dockless scooter sharing system (Lime) in Chicago. In New York City, low-income and racially diverse tracts are systematically underserved in static and dynamic utilities, while in Chicago, inequities arise from underutilized resources in low-income southern areas.