Socio-economic explanation of urban sprawl: Evidence from Switzerland, 1970-2010

The term urban sprawl is often used to describe apparent inefficiencies of spatial development, including disproportionate growth of urban areas and excessive leapfrog development. In Switzerland, where open space is a scare resource, sprawl takes place all over the country. It goes at the expense of high quality soil which is perceived as the most prominent negative effect. Proceeding from the monocentric city-model, urban economists confirm that urban sprawl is driven by fundamental economic forces such as rising incomes, population growth and low commuting costs. In Switzerland, all these factors have been quite pronounced over the last decades indeed and they should have a high explanatory value. Still, there is the question whether these forces are sufficient to explain suburbanisation also in recent decades. We build on traditional models regressing sprawl on mobility behaviour, rising income and population growth as explanatory variables, and extend the model with other explanatory factors such as change in life-styles (e.g. preference for single-family housing), demographic structures, employment distribution/structure, and commuting. We expect e.g. that a growing number of single households accelerates urban sprawl. Most of the urban economic studies on the drivers of urban sprawl focus on the periphery of great metropolitan areas and do not cover more than one period. Furthermore, they usually use simple measures to capture the development of the settlement structure such as total or per capita soil consumption. Yet, spatial patterns of soil consumption such as the density and spatial distribution of settlements and its development are not taken into account. We will fill this gap by using the recently developed metrics of urban sprawl (Jaeger et al. 2010) that incorporate density and spread of settlement structures and thus allows us to measure sprawl more comprehensively. Our analysis is based on an exceptional, temporally and spatially consistent dataset (including the newly developed comprehensive metrics for urban sprawl), encompassing all Swiss municipalities and covering a time-span of 1970 to 2010 with one observation per decade. This allows us to examine, whether and how the determinants of growth change across time and whether the conventional monocentric city model has more or less explanatory power in earlier or later decades. Such insights will provide a valuable contribution to our understanding of the phenomenon of sprawl. We propose to present first results of our analysis at the ERSA conference in St. Petersburg.