Proceedings of the International Conference on Changing Cities II:Spatial, Design, Landscape & Socio-economic DimensionsISBN: 978-960-6865-88-6, Porto Heli, Greece , June 22-26, 2015

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

C. Silva LoveraThe Bartlett School of Planning, Faculty of the Built Environment, University College London - UCL,

Central House, 14 Upper Woburn Place, London, UK.

*Corresponding author: E-mail: c.lovera@ucl.ac.uk, Tel: +44 020 76 79 7502

Abstract 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. Keywords: urban sprawl; (post)suburban development; undeveloped areas; interstitial spaces; urban morphology

1. INTRODUCTION

Although recent contributions about urban sprawl regarding its morphological aspects and impacts share a common definition, there still remain controversies related to conceptual approaches for its technical measurement, externalities and contributions. Indeed, Galster et al. [1] posit that, because of the complexity of measurement, it is not possible to determine an area as sprawl since sprawl is an ongoing process of transformation. Instead, it is proper to define a degree of sprawl, prior boundaries definition and factors involved [1]. Nevertheless, a common ground among academic analyses describes urban sprawl as scattered growth where traditional suburban developments become post-suburban as they provide evidence of economic and functional self-sufficiency [2].

Despite differing positions, it is clear that the emphasis of sprawls definitions has been mainly focused on the impact of built-up areas instead of undeveloped ones although these have an important role as they determine morphological and functional aspects of (post)suburban environments. Different entities such as pieces of countryside, geographical restrictions, protection buffers, speculative lands, protected areas, open spaces, brownfields, farmlands, forest lands, closed infrastructural facilities, green corridors and others appear as urban gaps or what I termed as interstitial spaces between developments describing narrow coexistences between planned and unplanned areas.

Considering the presence of these interstitial spaces, it is possible to assert that they are triggered by different factors and have diverse impacts. Moreover, some urban gaps have been included into the planning system but most of them appear as unexpected outcomes of planning. Considering that the literature addresses partial dimensions regarding these spaces, in this paper I discuss the presence of undeveloped or underdeveloped spaces as factors that explicitly appear in the planning machinery in different ways and with concrete links with urban morphology.

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After a conceptual discussion about undeveloped areas, in the next section I synthetically discuss three study cases where those appear as a result of different degrees of balance between public and market forces, taking part into the planning system at different scales and shaping the urban morphology of the expansion including social, economic and environmental impacts. The first case I discuss is the Finger Plan of Copenhagen and its emphasis on open tracts where the planning fabric determine its morphology as wedges that take part in the urban environment. The second case is the Randstad zone in Holland, where open tracts appear as a result of a major policy for protecting the Green-Heart and market forces that drive urban growth mainly in conurbation zones into the urbanized ring. Finally, Santiago de Chile illustrates the presence of built-up areas and interstitial spaces as a result of planning initiatives addressed case by case where public forces mainly regulate free-market forces operations at different scales. This study is based on secondary literature review for supporting the case of the Copenhagen and the Randstad zone and fieldwork data collection in Chile between 2012 and 2014.

2. (POST) SUBURBAN SPRAWL AND INTERSTITIAL SPACES

Although the subject of urban sprawl has been extensively addressed in the literature, it still remains as an open agenda considering differing positions about its origins, impacts and contributions for the understanding of the urban expansion phenomenon. In short, the sprawl debate has been mainly driven by the housing debate and its ideological meanings and in regards of its social, economic and environmental detriments as major counterpoints for those who describe sprawl as a factual issue that attends population and employment growth [3,4,5,6,7]. However, this debate has been shifted to a closely related literature about suburbanization processes with open questions regarding a more complex stage of fragmentation characterized by diverse land uses, socio-spatial diversity, polycentricity and functional independency at different scales [2,8]. The debate has shifted from a suburban to a post-suburban setting as part of the groundwork for understanding urban sprawl as a verb instead of as a noun where issues of the degree of change and boundaries are crucial for characterizing a place as a scattered one beyond its morphological aspects [1,2,8,9,10,11]

In this light, a conceptual and technical difficulty in describing sprawl pertains to spatial boundaries, which help to identify territorial units. In part, this difficulty appears because sprawl is a multifaceted phenomenon made up by densified areas but also undeveloped lands and open tracts where boundaries can be located. The presence of undeveloped areas in between developments illustrates the core of discontinuity which is one criteria included by Galster [1] in order to define sprawl indexically. Indeed, this criterion determines the distinction between different types of expansive growth where sprawl appears as a specific one. In Galsters words: discontinuous development could be characterized as sprawl in some cases but something else in others. Thus, the development of planned urban centers with moderate to high densities, separated along a transportation corridor by greenbelts or open spaces, might not be characterized by some commentators as sprawl1 [1]. Elements of discontinuity such as bodies of water, protected wetlands, forests, parks, slopes, or soils; and freeways, interchanges, or other public reservations and facilities2 [1] illustrate the importance of natural spaces as well as brownfields, landfills, farmlands, public spaces and other undeveloped areas and open tracts that define the set of gaps that, in turn, define sprawling conditions [12,2,6,13].

These gaps have been addressed by the literature on differing categories such as open spaces which are not necessarily undeveloped or derelict lands which are often former industrial areas. Thereby,

1 See Galster, G; Hanson, R; Ratcliffe, M; Wolman, H; Coleman and Freihage, 2001. Wrestling Sprawl to the Ground: Defining and Measuring an Elllusive Concept. Housing Policy Debate, 688-7172 Ibid: 690

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it is possible to see that particular definitions are also partial as they point to specific areas in sprawl and several dimensions have been left out.

The discussion about vacant lands, for instance, arises at the early twentieth century for describing any undeveloped land including small areas such as squares or parks, geographical accidents, parcels owned by private firms for future extensions, speculation lands or reserves for social facilities such as schools, religious or public services, mainly associated to previous architectonic facilities. In this vein, most of the literature refers to vacant lands in order to point to former industrial plots often claimed for regeneration, revamping processes or new regulations [14,15,16].

At an urban scale, the debate about Non-Urbanized Areas (NUAs) includes descriptions of open spaces as a network of green-infrastructures which tend to improve the quality of the entire urban environment including fringes, suburban and central areas. It includes farmlands, parks, river canals, forested roads and others up to squares inside the city. At any case, its contributions have been discussed in regards of its environmental potentials, suitable for promoting wild life and landscapes [17,18,19]. Regarding these areas, one body of literature illustrates NUAs technically that is, based on their chemical and biological properties; on the other hand, NUAs have been addressed from its political, economic and social influences at different levels of governance and policy-making processes. Both of them support the discourse of sustainable development and ecological modernization where NUAs tend to be promoted as open or empty urban gaps. [20]. A similar approach refers to green-infrastructure as areas that support new socio-economic potentials regarding protection of natural ecosystems, biodiversity promotion and spatial heterogeneity [21, 22].

Technically speaking, open spaces in cities also support the reduction of impacts of natural disasters especially in dense urban areas without natural surfaces for facing storm events and slope collapse [23]. Concerning economics, open spaces are potential areas for new developments if they are nearby infrastructure such as roads or railways and nearby services such as schools, markets, health services and others [24,25,26]. Socially speaking, these spaces provide specific features for making places singular and when they have integrated functions, encourages contact between people and reduces perceptions of insecurity [27,28,29,30].

From a morphological approach, the definition of the interfragmentary space [31] describes spaces between fragments based on the assumption that the city is made up by fragments and spaces in-between which define the interfragmentary space. Vidals definition emphasises the morphological dimension of urban fragmentation at different scales where the interfragmentary space could be understood as a place for spatial articulations or extensions [31]. In Vidals categories of interfragmentary space, the networks creation apply to the urban scale and describes an area made up by different types of nets such as channels, energy supply systems, pipes, a footbridge, a tunnel and others, no matter if these in-between spaces are built-up or are physically close. However, and considering these examples, interfragmentary space does not necessarily imply open or undeveloped space.

In a more conceptual approach, concepts such as terrain vagues [32] and non-places [33] apply for architectonic scales including social and temporary dimensions and have been used for describing any form of spatial vacuum or situation in-between buildings mainly former industrial lands or residual spaces and encompassing short temporary events determined by transitions between two or more situations such as the queue in bank or the virtual wait on a telephonic conversation.

As it is possible to see, neither empirical nor conceptual approaches for describing undeveloped areas and open tracts necessarily help to better specify urban sprawl or encompass the entire

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spectrum of different categories of undeveloped areas at different geographical scales and geographical distribution. So, the term interstitial space has been coined for embracing the set of undeveloped areas and open tracts in cities, particularly for urban sprawl, as another entity in cities that deserves a closer inspection in order to explore its nature, contributions and implications. In this case, the paper explores the implication of interstitial spaces in the urban morphology and as a first approach I examine three different cases where interstitial spaces appear as part of the planning system with different prominence. These cases describe urban gaps as entities with different degrees of importance and how they shape the urban morphology illustrating their explicit role into the planning machinery up to its presence as random outcomes of less controlled processes in planning.

3. EMPIRICAL EVIDENCE OF PLANNED/UNPLANNED INTERSTITIAL SPACES IN THE (POST)SUBURBAN EXPANSION

The cases presented in this section were selected to illustrate the role of interstitial spaces - not only as morphological entities which are coming along with built-up areas and shaping the sprawling process - but also as explicit/implicit components of the planning machinery articulating social, political and economic forces. The first case is the Finger Plan of Copenhagen presented in 1948. We use this example to illustrate how open tracts in fringes have been introduced as a predominant factor for defining the general urban morphology and determining narrow coincidences between the ideal plan and the factual development. The second case is the Randstad zone of Holland where open tracts define a combination of two categories of interstitial spaces: a regional interstitial space strongly protected by the green-heart and metropolitan interstitial spaces defined by conurbation zones between different towns and cities which are left flexible for the operation of market forces. Finally, the third case is Santiago de Chile, a country where the planning system is mainly driven by market forces and regulations which promote a pattern of development mainly based on outer densification processes in fringes. In this last case, interstitial spaces seem to be accidents in planning or unexpected outcomes with differing properties and potentials.

3.1 The Finger Plan of Copenhagen and planned interstitial spaces as wedges The plan has been largely discussed by scholars from its beginning in 1948 because of its similarities to a hand with fingers (finally nicknamed as The Finger Plan) but also because it has also inspired several analyses regarding the relationship between the urban morphology and policy-making processes. Aside from its morphological aspects, the balanced attention between built-up areas and natural landscapes defines a particular view regarding how open spaces are part of the urbanized environment as a bi-dimensional entity conceived as the city and where the status of open spaces is as important as densely developed ones This tenet is not unique to Denmark but also appears to apply in other Nordic countries where the cross-sector logic seems to be undertaken at different levels (even trans-national) and under jurisprudence of different ministries such as those for housing, urban planning and the like. Indeed, it has been assumed as part of the remit of local government; as part of urban-economic modernization [34]; as an element in the management of the environment and natural resources [35,36,37]; and, in the case of Sweden, where housing and urban issues are complemented with Information Technology policies [38]. This cross-sector logic seems to be part of a shared code about how the human environment emerges as a unity made up by built-up and non-built-up spaces and also illustrates the presence of public forces in settling plans over time. In fact, the Finger Plan was defined soon after the end of the World War II and still remains as a major guide. In this vein, the strong presence of nature in the spatial planning and policy making of Nordic countries has encouraged long-term territorial policies where the city depends on rural areas and regulations for environmentally friendly infrastructures and reconversion of internal urban spaces in order to promote nature [39]. Additionally, a major part of population is currently living in peri-urban locations where many commuters have begun to change their urban daily-life practices. Thereby, the boundaries between urban and rural have become diffuse and

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many people have decided to live in the countryside but work in urban areas, closer to services and infrastructure [40].

In short, the original proposal was oriented to safeguard important fragments of the countryside in order to promote a harmonized urban growth based on the creation of a series of densified zones under the scheme of fingers interspersed with series of interstitial open tracts as 'wedges' which would penetrate the city as near as possible to its main core (Figure 1). The functions of these interstitial wedges were originally conceived as natural landscapes, ecological corridors for wildlife, farmlands and temporary low-density activities related to leisure, recreation, sports grounds, forests, grassland, agricultural areas for public visitors, parks and minor recreation facilities within ecological corridors. The peri-urban areas in the north and north-west are mostly open for agricultural land and extensive forests in order to preserve wildlife, all accessible for the public and defined by a morphologically organized scheme of urban growth [41,42].

Figure 1. At the left, the original scheme for the greater Copenhagen that illustrates the morphological analogy between a hand with fingers and the urban map. At the centre, the scheme of the city made up by its interspersed open spaces as wedges and densified axes. At the right, a contemporary map of the greater Copenhagen (source: authors image based on Regional Planning

Office, front cover-1947 and Naes et al, 2009)

The original plan (an even some its precursor plans from the 1920s) has been an important basis for all further developments over the subsequent 60 years and was not only conceived as a traditional plan focused on planning for growth but also for the preservation of open spaces [42]. Notwithstanding the definition of an explicit morphology and functionality for interstitial spaces as part of the citys growth, some critics argue that the facts of geographical restrictions made the urban form an outcome of inevitable handicaps. Actually, Vejre argues that the considerable reputation of the plan is in part only a myth when one considers that most of its morphological definition is a product of physical accidents such as lakes and old forests precisely located in wedges [41]. Despite this, interstitial spaces in Copenhagen have been steadily present as long-standing criteria and irrespective of its origins they have determined the role of public forces in policy-making for promoting urban growth as well as protecting natural landscapes.

3.2 The Randstad and the protected green-heart with metropolitan conurbations areas The case of the Randstad zone in Holland is one that describes a regional urbanized area morphologically defined as a ring made up by the head cities of Rotterdam, The Hague, Amsterdam and Utrecht and other several towns in between. These towns circumscribe a large piece of countryside well-known as the green-heart that has been maintained for supporting agricultural production. Also, in between towns and cities there are many smaller undeveloped spaces which host conurbation processes driven by connectivity infrastructure and land-uses

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oriented to promote public activities such as parks, urban farmlands and ecological reservations. This is an urban constellation made up by urbanized areas and spatial gaps in between that surround a large scale open tract as a centre of the entire urbanized region (Figure 2).

As the Randstad zone has been considered as one of the most urbanized areas in Europe, it is also well-known that policies for preserving natural environments and the open countryside have been prioritized from the 40s at different periods. As well as the Finger Plan, the fashioning of the Randstad area has seen different levels of cross-sector coordination including participation of governmental agencies, universities and scholars, professionals, social and public institutions which not only involve housing and planning issues but also agriculture and natural environment agencies. According to Batten, Randstad planners aim to preserve its agricultural Green-Heart and the spaces between its main cities [43]. The aim is protecting a fertile area from urban encroachment and promoting open spaces based on the assumption that natural landscapes offer attractions to urban spaces and provide sociocultural identity [44,45]. These have been important criteria from the beginning of the Randstad plan. Indeed, in 1951 the Minister of Reconstruction and Housing appointed a commission to address the population growth after post-war migrations in the western part of the Netherlands and as a result, in the early 1958 this commission published the report The Development of the Western Netherlands focused on the urban form [45]. In this plan the preservation of the green character of open spaces between major cities (the so-called buffer zones) was posited and was established to keep them at least 4km wide. Also, on a larger scale, the plan argued that the open area located in the middle of the ring made up by cities and towns that define the Randstad should be preserved installing the concept of the Green-Heart. Finally the urban growth would be redirected outwards instead of inwards as a way of protecting the central area [45].

Figure 2. At the left, the Ranstad Zone proposal (front-cover page 1958 official report cited in Lambregts and Zonneveld, 2004). At the centre, the scheme of the regional city made up by the

central green-heart and the urbanized ring. At the right, a contemporary map of Randstad Zone in Holland (made by the author based on Fazal, Stan and Toppen, 2012)

As public institutions and private initiatives kept the interest in well-located natural landscapes, the Randstad zone keeps open tracts as mechanisms for capturing land values and as attractors for services supported by efficient corridors of infrastructure [46,47]. Thus, on the one hand, the regional open space - the Green-Heart - appears as an agricultural productive area that supports the regional economy. On the other hand, spaces between towns promote new developments increasing land values in regards of its proximity with the countryside.

In that vein, the presence of open spaces differs in terms of regulations. Whilst conurbation areas are flexible for promoting new developments, the Green-Heart is strongly regulated. This double condition flexible/regulated recognizes both urban growth and the importance of interstitial spaces. Based on this, the planning system also transfers conceptual definitions commonly used for the urban realm towards natural spaces which are granted the same status equal to buildings or infrastructure with implications for investments and cultural identity. Thereby, many of the urban

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gaps in the Randstad zone have been classified as 'landmarks' as well as some outstanding architectural projects. Indeed, the national planning policy has recognized 35 icons of Dutch spatial planning where at least 17 of them are natural landscapes that remark upon the identity of the entire polycentric area [48].

3.3 The case of Santiago de Chile and the piecemeal process for interstitial spaces production Different from the aforementioned cases where the planning system holds a predominant position within the development debate, Santiago de Chiles urban growth shares common patterns in planning with most of the Latin American cities where its constitution defines the State role as one of a regulator of private initiatives with a role in subsidising low-income families [49]. This condition basically circumscribes the public sector to defining norms and regulations for private sectors initiatives and as subsidiary of low-income families. As a result, the system is often regulating factual situations and illustrates difficulties for planning in advance. Thereby, the urban growth pattern appears as a steady outcome from the current nature of the Chilean planning system, which was consolidated in the middle of the 70s, strengthened in the 80s and confirmed in the 90s until today. This condition determines the production of urbanized areas as a piecemeal process where particular initiatives shape the overall urban morphology case by case based on the aggregation of new outer areas mainly driven by the housing demand. In the last 30 years this ongoing suburban development has set up an apparently uncontrolled expansion in Santiago properly identified as sprawl [50, 51] with its associated spatial gaps in between. This sprawl pattern has been lately criticised by different sectors, scholars and practitioners because of its negative consequences for the entire urbanized area such as environmental degradation, high levels of residential segregation, high levels of air pollution, poverty concentration, territorial disparities, increment of travel times and inefficient land uses [52,53]. However, other scholars, developers and some policy-makers have assumed that this sprawl pattern has been the natural consequence of steady economic growth and for giving large-scale solutions to an increasing demand for affordable houses and the lack of available land [54,55]

In this context, many of industrial, infrastructural and agricultural lands which were originally non-urban facilities have been left inside the urbanized area as a result of the scattered expansion without keeping its competitive activities or simply underused. Thus, Santiagos sprawl landscape is made up by developed lands but also interstitial spaces that define a patchwork of urbanized areas with empty lands in between. These spaces are manifested at different scales defining different magnitudes from regional, metropolitan and urban. These scales embrace conurbation areas, former airports, military bases, farmlands and agricultural research centres, railways lines, brownfields, landfills, metropolitan facilities and other smaller vacant plots mainly as a result of geographical restrictions, land-use definitions and speculative lands. Many of these spaces are currently well located nearby transport infrastructure, energy supply, services and consumption power due to its populated surroundings (Figure 3)

Some of these spaces still have their original land uses but they are not competitive at all or simply cannot grow as their surroundings have been urbanized. Thereby, many of these internal spaces become closed environments due to the nature of their activities and define strong boundaries to the continuity of the urban development. As a result, these areas fall into drabness and disrepair, some of them are disconnected as they are surrounded by protection security buffers instead of neighbourhoods or urban infrastructure. So, the decline of these areas is actually opening questions about their impacts and possibilities for their contributions to future urban development and what could be the proper way for getting advantages from their current good locations. As far of leaving these areas simply empty considering environmental properties or the creation of wild environments [56,57], several urban initiatives have been oriented to create land-value based on their capability for hosting urban functions such as housing projects or infrastructure. However, most of these initiatives have not been successful and have had major political and economic

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impacts. Actually, some of them have taken more than 10 years in debates, discussions, plans and projects, political commitments, professional consultancies and even expensive works that only illustrate partial achievements supported by extended discussions regarding how to improve or reclaim these areas for the planning fabric.

Figure 3. Santiago de Chiles map and its open tracts. The most sprawling areas are to the Northern and Southern (residential neighbourhoods, industrial lands, farmlands, conurbations). To the West there are infrastructural and geographical restrictions and to the East there is the Andes mountain

chain (Authors map based on Echeiques map 3)

4. CONSLUSIONS

Urban sprawl has been analysed as a multifaceted issue of built-up places. However, there is conceptual and empirical evidence about the presence of a large spectrum of what we termed as interstitial spaces that also shape the (post)suburban development including areas for agricultural, infrastructural and socio-economic services that make the sprawl a more complex phenomenon.

In this vein, the lack of attention focused on these spatial gaps implies a conceptual constraint on analysis within urban studies including these areas more fully in our analysis can lead to a better comprehension of current patterns of urban expansion and the possibilities for planning the effect change to the extant pattern of sprawl in many metropolitan areas. Indeed, although there is little evidence of how different planning systems make efforts to include such spatial gaps into the urbanized environment, there are also many cases where these entities appear as unexpected outcomes or less controlled processes of planning supported by a logic of muddling through in decision-making including all forms of urban policy.

3 Echeique, M., 2006. Las vas expresas urbanas: qu tan rentables son?. In Santiago: Dnde estamos y hacia dnde vamos. Ed. Alexander Galetovic. 462-488. Centro de Estudios Pblicos, 2006. Santiago, Chile

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In those cases, a common reaction is to pressure for applying in-filling policies, promote flexible regulations or simply reduce the issue to physical constraints instead of understanding the potential of such spaces as interstices. These unexplored potentials of interstitial spaces and their long-standing presence as part of the urban morphology entails a deeper revision of policy-making and its role in the planning system. Thereby, interstitial spaces deserve a closer inspection in terms of their contents, meanings and geographical scales in order to define more complex agendas for understanding current patterns of (post)suburban growth.

Acknowledgments This research has been supported by a PhD studentship from the National Commission of Science and Technology - CONICYT - Chile, Becas Chile Program, code 72110038. The PhD research is conducted by Cristian A. Silva Lovera under supervision of Professor Nicholas Phelps at UCL, London, UK.

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