Portal de Periódicos da CAPES

Great cities look small

2015; Royal Society; Volume: 12; Issue: 109 Linguagem: Inglês

10.1098/rsif.2015.0315

1742-5689

Aaron Sim, Sophia N. Yaliraki, Mauricio Barahona, Michael P. H. Stumpf,

Land Use and Ecosystem Services

Great cities connect people; failed cities isolate people. Despite the fundamental importance of physical, face-to-face social ties in the functioning of cities, these connectivity networks are not explicitly observed in their entirety. Attempts at estimating them often rely on unrealistic over-simplifications such as the assumption of spatial homogeneity. Here we propose a mathematical model of human interactions in terms of a local strategy of maximizing the number of beneficial connections attainable under the constraint of limited individual travelling-time budgets. By incorporating census and openly available online multi-modal transport data, we are able to characterize the connectivity of geometrically and topologically complex cities. Beyond providing a candidate measure of greatness, this model allows one to quantify and assess the impact of transport developments, population growth, and other infrastructure and demographic changes on a city. Supported by validations of gross domestic product and human immunodeficiency virus infection rates across US metropolitan areas, we illustrate the effect of changes in local and city-wide connectivities by considering the economic impact of two contemporary inter- and intra-city transport developments in the UK: High Speed 2 and London Crossrail . This derivation of the model suggests that the scaling of different urban indicators with population size has an explicitly mechanistic origin.