Cities in Worldwide Air and Sea Flows: A multiple networks analysis

Cities and transport networks have been intertwined through history and are still related despite the impacts of telecommunications. While each transport network has its own purpose, actors, rules and regulations, the position of cities in such networks reveals their complementarities. This paper analyzes the hierarchy and the specific roles of cities in two worldwide transport networks: air passengers and maritime freights. These two networks were chosen despite noticeable differences in terms of spatial and economic organization, albeit they both have essential respective roles in urban development. Three levels of delineation of urban areas are tested in order to evaluate their influence on network structure, hierarchy of centrality, and correlations between networks. The measurement of specialization and polarization among cities allows proposing a typology where “independent gateway cities” occupy bridge positions within and between nodal regions. This research clarifies the interdependency between cities and between networks in the processes of globalization, regionalization, and urban development