Expansion of the built-up areas in Finnish city regions - The approach of travel-related urban zones

Finnish city regions have expanded rapidly due to urbanisation and urban sprawl, most recently in the 2000s. In this study, an approach of travel-related urban zones is introduced to enhance the interpretation of urban expansion in relation to previous land cover and urban form. The urban expansion of 34 Finnish city regions was studied by combining national CORINE Land Cover (CLC) data with socio-economic data using GIS. The regions were analysed by dividing them into zones: pedestrian, public transport, and car zones. The approach is applied from the theory of three urban fabrics, where the fabrics have distinct spatial characteristics and have been shaped by the evolution of transport systems. The aim was to determine which land cover classes were the most exposed to urban expansion during 2000-2012, and how large a share of the new residential floor space was located in previously developed areas in each zone. All the regions expanded the most into former forest areas in the fringe of the city, i.e., in car zones. On average, 77% of the area of urban expansion was previously classified as green spaces suitable for recreation. In the majority of the regions, the largest share of new residential floor space was concentrated in car-oriented locations that were not previously developed. The built-up areas grew even within regions with a declining population, exceeding the population growth altogether by a factor of 1.6. The study supports the previous findings on the sprawl-type urban expansion of Finnish cities, and implies insufficient steering of the urban development with negative environmental impacts in the 2000s. However, for the largest cities, the analyses also show signs of shifting towards infill development policies in public transport zones.