Airspace network design for urban UAV traffic management with congestion

To support the safe and widespread use of unmanned aerial vehicles (UAVs) in urban environments, industry stakeholders and regulatory authorities are partnering to develop urban airspace traffic management systems (UTMs). UTM system providers face strategic decisions in how to design and manage airspace available to UAV flights. We consider a provider that plans to open an urban airspace in which UAV flights are routed above existing roads in 3D corridors corresponding to segmented altitude levels. The provider aims to select a subset of the road network to form an air-network with the goal of providing safe and cost effective service for UAV traffic. The air-network selected must provide routes that respect UAV technology restrictions, and must have adequate capacity to support the expected flight volume. We develop a 3D airspace network design model that selects a subset of roads whose 3D projection into the sky will be used for routing flights. The constrained system optimum (CSO) traffic assignment model is used to evaluate the quality of the network; the CSO user constraints represent battery restrictions while minimizing the total travel time ensures realistic routing in the face of congestion. To incorporate the 3D nature of flights, we use simulation to calibrate a Bureau of Public Roads capacity parameter that reflects the multiple vertical layers of airspace made available when a road is selected for the network. We introduce a methodology to derive candidate maps for urban areas and use it on open-source data to build a case study for Chicago city center. We assess the impact of budget, congestion, minimum-path deviation, and demand patterns on network designs.