Assessing urban containment policies within a suburban context—An approach to enable a regional perspective

Regarding suburbanisation, land policies in many countries have undergone profound changes over the past 20 years. While experiencing high growth rates of urban land, policies were reconsidered and adapted with the goal of limiting land consumption in favour of a more sustainable urban development. These changes aim at a higher effectiveness in steering urbanisation processes to limit environmental impacts, but also are criticized regarding possible effects on a sufficient supply of housing. To this regard, also German urban planning policies show considerable dynamics. After several urban containment policies were introduced, the question arises on how to empirically assess their effects. Therefore, monitoring approaches with a regional perspective become more and more relevant, as polycentric, suburban settlement structures constitute the spatial but also institutional context of urban containment policies. Considering suburbanisation as a global phenomenon, we develop a monitoring approach, which allows for a quantitative and qualitative assessment within suburban settlement structures. We propose a set of indicators that integrates urban structure, regional accessibility and usage by population. As data is scarce for a city-regional perspective, we combine geospatial methods for an automatic identification of building types from topographic data and maps, for measuring multi-modal accessibility and for small scale demographic analysis. The approach is applied to the case of a German city-region with splintered planning institutions. The results of the small-scale, but also comprehensive regional analysis allow for a detailed discussion of effects of policy changes on the settlement structure.