Supra-local spatial planning practices and suburban patterns in the Barcelona and Milan urban regions

Despite metropolitan authorities and regional governments might not have direct spatial planning competencies on local land-use transformations, they can intervene (control and steer) on planned local development by means of their ‘intermediating capacity’. In the effort to relate supra-local governance and spatial planning factors with localised urban sprawl, I examined supra-local spatial planning practices and suburban patterns in the Barcelona and Milan urban regions by using a comparative, case-based, multi-data and multi-method research strategy. The analysis of soil sealing data shows that the Barcelona case presents a lower proportion of high and medium suburban areas (16–64% soil sealing) and less land consumption than the case of Milan, as well as a higher population density and land-use efficiency. The analysis of the supra-local spatial planning practices at the regional, metropolitan and provincial level (22 expert interviews) suggests that these different spatial patterns can be partially explained by different types of intermediating capacity. Findings show that more compact and less suburban spatial patterns are found when supra-local (regional) actors assess land-use plans by using both quantitative (control) and qualitative (steering) criteria and when binding area-wide (metropolitan) plans are present. In turn, political alignment across municipalities appears to be in itself not sufficient to limit suburban territorial expansion. •Supra-local intermediating capacity is composed by control and steering practices.•The Barcelona urban region is comparatively more compact than the Milan one.•Supra-local spatial planning practices can influence local urban development.•Qualitative assessment criteria in planning are associated with more limited suburban patterns.•Binding metropolitan plans are associated with urban compaction.