Evaluating the impact of Urban Air Mobility on ground traffic efficiency: A multi-scenario simulation study

Urban Air Mobility (UAM) is advancing rapidly, and its services are inherently linked with ground transport networks, making their impacts on traffic flow and efficiency a critical concern for urban mobility planning and policy decision-making. However, research on the implications of UAM for ground transportation remains limited and contested. Existing studies show divergent findings at the system-wide level and often overlook spatial heterogeneity and localized effects. This study develops an extended SUMO-TraCI framework that (i) incorporates realistic car-based first-/last-mile access and dispatch mechanisms, (ii) enables dual-scale analysis by capturing both system-wide traffic efficiency and localized congestion around vertiports, and (iii) supports multi-scenario testing, providing a broadly applicable framework for UAM evaluation. Based on five scenario experiments varying vertiport numbers (10, 30, 60, 80, and 100) relative to a baseline, UAM demonstrates modest yet positive citywide impacts on traffic flow reducing VKT and TTT modestly under the baseline eligibility setting, while sensitivity tests further reveal a non-linear and saturating benefit pattern around the 60–80 vertiport range as infrastructure density increases. Network-level spatial patterns indicate slightly greater relief on peripheral corridors and more frequent minor increases in central areas, with localized changes more noticeable on high-capacity roads than on local streets. This study introduces a scalable, multi-scenario evaluation framework for understanding and managing the multimodal impacts of UAM, providing actionable insights to guide evidence-based UAM planning and support sustainable city development.