Urban sprawl : Controlling urban sprawl – limiting soil consumption

Soil consumption due to urban sprawl has increased dramatically since 1950, and – without countermeasures - considerable increases in sprawl are predicted by 2050. Many measures to control urban sprawl have been discussed, some appear to be successful (e.g. intensification of settlement area) but many have been applied so cautiously that they have had little effect.

The project aimed at developing a comprehensive understanding of the drivers of urban sprawl. The team used advanced spatial models to geographically allocate sprawl and corresponding soil consumption patterns for various future scenarios.

The results show that wealthy and well accessible municipalities with a high share of commuters have been prone to urban sprawl and soil consumption since 1970. Population growth cannot adequately explain sprawl before 2000, but it has been a driver ever since. An increasing demand for housing space per capita was a particularly strong factor in pushing urban sprawl until the turn of the millennium.

The team carried out the first fully representative survey of Swiss planning and policy instruments that steer urban development at municipal level. The choice of instruments depends heavily on the population size of the municipalities. Larger municipalities have more planning capacity, allowing them to effectively implement incentive-oriented policy instruments. Small and rural municipalities often lack the planning resources needed to implement such policies. Instead, they tend to rely on traditional and regulatory policy instruments.

Our predictive models show that, depending on the scenario used, urban areas in Switzerland will most likely rise between 3 and 56 per cent until 2035. Urban development will – under the most extreme scenario – reduce the agricultural areas by 13 to 15 per cent by 2035 if no countermeasures are taken.

This is a comprehensive analysis of the drivers of urban sprawl using a long-term series of sprawl measurements (going back to 1934), a fully representative municipal survey, a Swiss-wide coverage of economic drivers, and spatially explicit models to estimate soil consumption.

Economically urban sprawl is mainly driven by accessibility and related commuting patterns. Political and fiscal incentives that encourage polycentric urban growth should therefore be combined with a strong campaign to establish local planning capacity in municipalities. It is necessary to support the coordination of planning efforts in regional planning units and to provide municipalities with accessible and affordable counselling opportunities. At the technical level and the level of the building codes, all efforts to reduce sprawl - such as intensification, gap-filling or limitations for urban development - should be enforced.

Controlling urban sprawl to limit soil consumption (SPROIL)