Patterns of Urban Spatial Expansion in European Cities

In representing urban sprawl, the decline in population and employment density from the city centre to the periphery has been identified as the main character associated with the spatial expansion of built-up areas. Urban spatial discontinuity, which occurs when the urban fabric includes built-up or green areas and a relevant share of vacant spaces, has gained recent attention. In this paper, we use Global Human Settlement Layer data to track urbanisation dynamics in European Functional Urban Areas (FUAs) from 1990 to 2014. We represent urban sprawl as the spatial expansion of FUAs associated with either or both declining population density and increasing built-up area discontinuity. We also consider the association with the demographic trends that have been described as the primary driver of urban spatial expansion. We use configural frequency analysis to explore the local association between the different characters of sprawl. We found evidence that urban sprawl effectively took differentiated forms across European FUAs. Even though FUAs have generally become less dense and more disperse, our results show that the extent of these phenomena appears to be more contained in recent years than in previous decades. Both elements of sprawl characterise FUAs with a shrinking population, confirming the decoupling of urban development policies and demographic trends in cities. The results call for better controlled urban development, favouring compact cities and subjecting land-use changes to a perspective of urban population growth.