Table 1 Urban airspace planning literature.

Metropolis project³⁶

Full mix, layered, zonal, and tubed

Optimal route geometry

Flow management, separation, and conflict avoidance

Considers only average regulation strictness

Presenting alternative scenarios

Limited static airspace planning in two models. Exclusive limitation of operation within obstacle-free airspace decreases mission range for smaller UAVs and increases mission time for emergency application

Singapore’s TM-UAS^37,38

Full mix (AirMatrix), over buildings, and over roads

N/A

Flight and risk management

Varying degrees of regulation

Presenting alternative scenarios

Limited static waypoint concept. Limited route optimization and flexibility with UAV types and sizes given only constant speed or random speed optimization limitation in traffic control

Australia’s Smart Skies project³⁹

Automated separation management system

N/A

Sense-and-Act Systems

Local current regulation

N/A

Limited model details. Limited route planning and optimization capabilities through the developed Mobile Aircraft Tracking System (MATS)

NASA UTM^40,41

Collision avoidance

N/A

Contingency management and re-routing

FAA regulation

Public safety illustration

Limited multi-modal airspace discretization and modification