Peri-urban residential neighborhoods at the margins current trends in urban growth: towards sustainable transition paths?

In Switzerland as in most European countries, the last decades of urban development have put much pressure on the environment due to uncontrolled urban sprawl. The existing peripheral residential built-up areas mostly composed of single-family houses are responsible for and subjected to many sustainability issues, which are expected to grow in the short/medium term. Focusing on urban and architectural design, this on-going research investigates possible paths for the future of peri-urban neighborhoods of single-family houses by 2050. The paper presents the intermediary results of several test-applications of prospective scenarios developed for two case studies in the urban region of Lausanne, Switzerland. First, this article briefly introduces the research framework of the peri-urban question in Switzerland by highlighting the specificities of the policy and territorial contexts. Second, it describes the design framework, focusing on the elaboration of a typology of peri-urban neighborhoods of single-family houses used as a preoperational tool to guide the design process. The core of the paper then focuses on the conceptual elaboration of four prospective scenarios foreseeing possible evolutions for peri-urban neighborhoods of single-family houses. To illustrate this approach, test-applications – in terms of urban and architectural design – are conducted in two existing neighborhoods. Finally, a limited list of indicators on density, land use and environmental impacts helps assessing the performances of each applied prospective scenario. The scenarios seek to be operational and feasible in a way to provide a decision support. The preliminary conclusions of the study highlight several initial conditions to bring peri-urban neighborhoods on a path towards sustainable transitions.

Peri-urban residential neighbourhoods at the margins of current trends in urban growth: towards sustainable transition paths ?

Judith Elisa Drouilles, Guillaume Lucas, Sophie Lufkin

In Switzerland as in most european countries, the last decades of urban development have put much pressure on the environment due to uncontrolled urban sprawl. The existing peripheral residential built-up areas mostly composed of single-family houses are responsible for and subjected to many sustainability issues, which are expected to grow in the short/medium term. focusing on urban and architectural design, this on-going research investigates possible paths for the future of peri-urban neighbourhoods of single-family houses by 2050. The paper presents the intermediary results of several test-applications of prospective scenarios developed for two case studies in the urban region of lausanne, Switzerland. first, this article briefly introduces the research framework of the peri- urban question in Switzerland by highlighting the specificities of the policy and territorial contexts. Second, it describes the design framework, focusing on the elaboration of a typology of peri-urban neighbourhoods of single-family houses used as a preoperational tool to guide the design process. The core of the paper then focuses on the conceptual elaboration of four prospective scenarios foreseeing possible evolutions for peri-urban neighbourhoods of single-family houses. To illustrate this approach, test-applications – in terms of urban and architectural design – are conducted in two existing neighbourhoods. finally, a limited list of indicators on density, land use and environmental impacts helps assessing the performances of each applied prospective scenario. The scenarios seek to be operational and feasible in a way to provide a decision support. The preliminary conclusions of the study highlight several initial conditions to bring peri-urban neighbourhoods on a path towards sustainability transitions.

2018

Quartiers résidentiels périurbains en transition : Comparaison multicritère de scénarios prospectifs à l'horizon 2050

Judith Elisa Drouilles

Since the Industrial Revolution, urban spaces have undergone a profound reorganisation in parallel with a transformation of society and lifestyles. Urban sprawl has become widespread in Switzerland, as in countless countries, due to continuous innovations in transport, exponential population growth, land speculation and the ubiquitous desire to live in a single-family house. This process has led to a dispersion of the city in rural areas, which today raises multiple questions regarding sustainability aspects. In response to the negative consequences of urban sprawl, the model of the polycentric compact city sets a reference for the expression of ambitious spatial planning policies. The context, very favourable to inward densification processes in areas well served by public transport, changes the perception of neighbourhoods of single-family houses by providing them with a status of unexploited land reserve. A growing number of projects is investing this emerging field of research to address the challenges of under-occupancy of housing, energy insecurity or the production of new residential areas. However, some neighbourhoods, located in peri-urban areas benefiting from a relatively poor public transport service, are on the margins of current investigations. Proactive approaches are still rare to provide answers to the challenges faced in these existing residential sectors. The aim of this doctoral thesis is to develop a decision-support framework to consider the future of peri-urban residential areas and their participation in the sustainability transition. Anchored within the European and Swiss contexts, the work questions the transformation potential of neighbourhoods by 2050. The approach is divided into four phases, the first of which consists in developing a typology of peri-urban neighbourhoods of single-family houses. This typology is the result of a method based on the successive reduction of the analysis scale, from the theoretical definition of peri-urban residential municipalities to the census of representative neighbourhoods in the Greater Lausanne area. The design of prospective transformation scenarios is part of the second phase of the research. The five scenarios â Caducity, Exclusivity, Opportunity, Urbanity and Mutuality â are derived from stagnation or transition trends of peripheral sectors, identified during interviews conducted among about 20 experts. The third phase consists in applying the scenarios to six existing neighbourhoods over a 35-year time horizon. The thesis does not have as its sole objective to carry out forward-looking work applied to concrete cases, by proposing a medium/long-term vision. Its innovative character also lies in the implementation of an experimental tool of building information modelling (BIM) at the scale of the neighbourhood to deal with the complexity related to the constraints of individual ownership. Considering assumptions of demographic and temporal calibration of projects, the fourth phase, of multi-criteria assessment, is enhanced by a dynamic analysis of evolutions. This assessment, developed in light of sustainability issues, highlights a considerable potential for improving peri-urban neighbourhoods, through energy-saving building renovations and the preservation of quality living standards. The path towards more sustainable futures also depends on the coordination of decisions at the neighbourhood level to go beyond the mere juxtaposition of individual interests.

EPFL2019

Entre ville et campagne

Sophie Lufkin

Environmental, social and economic concerns linked to the sustainable development of the built-up environment are increasingly calling into question models of territorial development based on urban sprawl. This is because the process of dispersed urbanization generates social inequalities; it is based on the extensive use of automobiles, and leads to increased spending on infrastructure networks. This phenomenon tends to be explained by the search for a combination of life in the city and life in the wide-open which creates new life-styles based on the extensive use of transportation and communication systems. The analysis of these emerging practices indicates that they arise from a double pressure exerted on the population: on one hand, attraction to rural and mountain areas, and on the other hand the economic and cultural dependency vis-à-vis the large urban centers. In this context, the regeneration of urban wasteland areas appears to be a strategy capable of favoring a better anchoring between urbanization and public transport. The dynamics of off-shoring enterprises has freed up a large number of plots that are however connected to existing networks, and benefit from good accessibility and sometimes enviable centrality. The requalification of industrial wasteland has been the object of much research in the nineties, which has led to establish as principles density, mixed use and the preservation of the industrial heritage (for instance Escher-Wyss in Zurich-West, Sulzer in Winterthur, ABB in Baden, SIP in Plainpalais-Geneva). In the same way, following the abandonment of some mobility structures, research has started to focus on the fate of urban railroad wastelands. These are considered to be strategic locations to develop "compact cities", attractive for habitat and favorable for the development of social and cultural activities. Several examples in Switzerland illustrate these attempts: Ecoparc in Neuchâtel, Zurich HB, La Praille in Geneva, etc. Today, in order to offer alternatives to the urban paradigm of the compact city we focus our attention on a different type of railroad wasteland. By regional railroad wasteland we refer to areas located close to a train station, either abandoned or in the process of being abandoned, and situated in suburban or periurban zones. Though these regional railroad wastelands present advantages similar to those of the urban wastelands in terms of accessibility to public transport, they are very different by their relationship to the landscape and nature. In addition, much more affordable land prices than in city centers allow more flexibility in the choice of programs and target users. In line with the thinking led by Thomas Sieverts among others, we attempt to go beyond the antagonisms between city and country, by formulating the hypothesis that these regional railroad wastelands bring an answer that is able to reconcile the aspirations to life in the country with the requirements of sustainable territorial development. The present research aims to explore a series of urbanism strategies induced by the simultaneous and inseparable presence of the railroad and natural dimensions, which constitutes the specificity of these periurban and suburban sites. In a first phase, in order to reveal these specific characteristics we conducted a typology exercise on a sample of thirty railroad sites located on the Geneva to Sankt-Gallen axis. It extends the whole length of the country from Lake Geneva in the southwest to Lake Constance in the northeast and goes through the main city areas of the country as well as several so-called calm areas. These thirty wastelands were measured, photographed, described, analyzed and finally represented according to an innovative methodology that combines architectural, urbanism and sociological approaches. This first phase concludes with the construction of the "face" of each site; beyond the fundamental distinction between urban and regional wastelands, it leads to the identification of six individual types. In a second phase, the focus moves to the project process. In order to understand precisely the mechanisms and the stakes at play, we have analyzed several case studies of urban wastelands in various stages of advancement, going from construction finished (Zurich-West), to the beginnings of the launch of a project (Fribourg), the first stages of construction (Zurich Stadtraum-HB) and planning in the course of development (Lausanne-Malley). We thus show the main obstacles to development, then the levers, triggers or planning instruments capable of surmounting them. Finally, in the last part, we elaborate development scenarios up to 2025 for three regional wastelands of the Lake Geneva urban hub, which come from a distinct group within the typology: Versoix, La Plaine and Palézieux. The project recognizes two scales of intervention: the train station and its immediate surroundings on one hand, and the extended perimeter on the other hand, which includes land within a 500 meter radius around the station. The developments of these two perimeters are intimately linked: the creation of a pole of urbanization may induce an improvement of the rail service and vice-versa. These two embedded scales thus constitute a complex dynamic system, within which specific, though coordinated urbanism strategies are implemented, and the stakes proper to each perimeter dictate these. For the station and its immediate surroundings, the goal is primarily to increase the hospitability of the site, that is principally to increase the symbolic role of the station, to plan the equipment and infrastructure necessary in view of the increased flows of travelers, and arranging the external space by accentuating the presence of vegetation, in agreement with the local character. All of these interventions lead to the creation of a "railroad landscape" which is the regional counterpart to the urban public space. Within the extended perimeter, the project strategy rests upon the recognition of five complementary qualities: inhabited, equipped, wild, productive, to be contemplated, whose proportions vary according to the territorial insertion of the wasteland. Densification is then effected in a punctual and targeted manner, in coherence with the logic resulting from the encounter between rail and nature.

EPFL2010