Urban sprawl and interstitial spaces: a conceptual definition for undeveloped areas and their morphological implications in planning

The term urban sprawl has been discussed as an increasingly complex and multidimensional phenomenon. However, understandings of urban sprawl have been mainly focused on built-up spaces instead of undeveloped ones - although the latter are just as crucial to comprehending this phenomenon. Indeed, multiple spaces such as farmlands, brownfields, geographical restrictions, public and green spaces, protection buffers, conurbation zones and others have been left within the (post)suburban expansion as part of its contents although they often appear as uncompleted ‘interstices’ or open tracts with unknown potentials. Thus, this paper addresses the set of undeveloped areas and open tracts – named here as ‘interstitial spaces’ - not only as another element of sprawl but also as a component of the planning fabric with its consequences on the urban morphology. Empirical evidence describes how its presence emerges at diverse conditions as a result of differing tensions between public and private forces