Urban Roads and Aerial Autonomy: Are Drones Safe Above Busy Roads?

Urban delivery by Unmanned Aerial Vehicles (UAVs), or drones, is a promising logistics solution. While a dominant vision involves drones navigating autonomously through complex open airspace, this approach demands advanced perception and control capabilities. In contrast, this work explores an alternative vision: low-altitude drone flight along obstacle-free existing road networks, leveraging digital maps. To assess the feasibility of this approach, we investigate the indirect risks associated with drone failures, specifically, the risk that a falling drone causes a traffic-related accident. We show that, under dry conditions, the score risk meets the aviation-grade safety expectations (usually 10−6 fatal injuries per flight hour) under any traffic level when vehicle speeds are low or moderate (below 50km/h), and under low traffic conditions (1 car every 100 seconds) when the vehicle speed is above 70 km/h. We also analyze the impact of contextual factor such as wet road conditions, and nighttime driving into the risk score: at low speed (30 km/h), the safety aviation requirements are always met. These findings represent a first step toward establishing the potential safety of road-aligned drone navigation in urban environments.