The world population is expected to grow further with a major increase in population living in urban areas. Exploiting the door-to-door concept to the full extent, a considerable part of conventional vehicles may be replaced by personal aerial vehicles. Cargo delivery system will the follow same philosophy using unmanned aerial vehicles. This brings up completely new challenges for future air traffic management in urban environments. The Metropolis research project investigates radically new airspace design concepts for the urban environments 50+ years into the future, which are extreme when compared to today in terms of traffic density, complexity and constraints. This work presents the results of simulation data analysis and a comparison of concepts of urban airspace design regarding organizational (complexity) metrics. The aim was to identify how the structure involved in the concept of urban airspace design influences the complexity of the traffic situation. In this work geometrical metrics, which are only linked to trajectory structure and not to the system used to process them, were used to measure complexity. A robust extension of proximity-convergence metrics as a compound metric has been developed for the ultimate concept evaluation.