Infoscience

Thesis

Entre ville et campagne: stratégies de densification qualitative ciblée des friches ferroviaires régionales

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.

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