Transport à câble aérien en milieu urbain: pertinence et pratique

The intense urbanization of cities has left few options when it comes to insert large mobility infrastructure they need to move their inhabitants. A surface rail network, a dedicated roadway bus line or any other mobility infrastructure such as a tramway at the urban surface represent challenging interfaces to set up, particularly because of level crossings and physical barriers that they induce in the urban space. To avoid this occupation of the surface and the resulting urban scars, a lot has already been invested in the underground. Whilst, the airspace is still very little exploited by urban transport systems. In order to deepen knowledge in this area, the research theme focused on the urban ropeways, a cable air transport system, which several innovative examples can be found in Latin America.

Relevant for whom? The research conducted is divided into two stages. As a first step, a sociological analysis made it possible to determine how urban ropeways are relevant for users and represent an interesting alternative to other means of public transportation. This analysis is based on a survey among users of ten public transportation lines in Switzerland and Brazil.

Relevance where? In a latter phase, the analysis concerns the project of urban ropeways in the urbanized areas. This transportation system can be considered as a complex project because of its constructive characteristics, at the territorial big scale. A sequence of large mobility interfaces projected along the ropeway path transforms connectivity, density, and public space. These different architectural objects of mixed use are connected in minutes by the cable and their strong presence in the urban landscape raises questions of relevance. Spread in the Rio de Janeiro, Lake Geneva and New York metropolis, ten cable routes are studied, taking into account the temporality of project progress and the degree of urbanization of the target territory. This evaluation of the project practice aims to determine the extent to which urban ropeways is likely to be developed in European territory, Swiss in this instance.

At the end of these analysis, the thesis makes it possible to conclude that urban ropeways have their relevance in European cities, but under fairly specific conditions.

Planification urbaine et usages des quartiers précaires en Afrique

Benjamin Michelon

Since 2000, declarations issued in rapid succession by the international community have aimed at setting goals to drastically improve the living conditions of slum dwellers while, in the same time, the slums dwellers increased by 4,5% per year in Africa. Simultaneously, we have witnessed changes in the manner in which city residents perceive space: in today's city, the relationship between places and flows constitutes the new living space and sense of belonging (Castells, 1996). With the changes in the information society, space of flows are transformed into power flows, concentrated in space of flows which dominates more and more space of places, peripheriques areas where flows takes place everyday. Using this theory as grid, it is to re-examine the evolution of urbanization in African cities and their shantytowns. Indeed, this process of domination of the space of flows has implications for the planning approaches and uses of space of place in slums. This dual vision, putting power to the flows of space valued by the elites'cities of the living spaces of places experienced by people, is used to observe, name and understand the past and the future of cities. These elements have resulted in the formulation of a number of questions that have served as guidelines for this research. This research first targets the development of the urbanization process and the role of precarious neighborhoods: what measures are now being implemented by the authorities to reconcile the need to improve the competitiveness of African cities (advocated by donors) with the expectations of people in poor neighborhoods? In a second phase, the role of these neighborhoods' community areas is evaluated: are they a media to be valued and included in the projects to restructure the neighborhoods? Two assumptions have emerged from said questions. The first concerns the process of urbanization in African cities. This involves an analysis of the balance of power between the application of modernizing planning practices and the use of space by the residents of the neighborhoods. The second questions the role of community spaces as efficient public areas within the framework of projects to upgrade the neighborhood. The expected results of this thesis aim i) to understand the evolution of these precarious areas in the building of African cities, ii) to learn about the place and the role of community spaces and to learn from neighborhood upgrading projects. For this study, two cities were chosen: Douala (Cameroon's economic capital) and Kigali (Rwanda's political capital). For each, two methodological perspectives were adopted: the first is a comprehensive study of the entire city, based on plans, planning documents, interviews with local officials, archive documents; and the second is as a local study carried out in a market area of the city, based on observations, interviews, a questionnaire developed from a representative sample of traders, and a social and spatial analysis of the neighborhood. This approach is therefore comparative (two cities and two districts), multi-scale (two scales of analysis), historical (identifying cultural, social and political customs) and interdisciplinary (even holistic to a certain extent, taking into account different disciplines such as law, economics and urban sociology). Ultimately, this study reveals both the local specificities and differences of each city. These dissimilarities were largely developed in the presentation of these territories. They are indeed important, especially for the city of Kigali, which is undergoing a process of post-genocidal reconstruction. However, it also appears that each city's path contains a significant number of common characteristics, mainly linked to the responses they provide to urban problems: globalization today tends to standardize practices. The first element common to both areas is urban duality. This process occurs first in an urban form. The African city today remains a binary geographical entity: the city that separated the indigenous people from the settlers was succeeded by a post-colonial city marking the separation between the inherited formal city and the informal city in creation. This urban confrontation can be seen as a form of inertia, defined as a rectilinear uniform advance, suitable for the fabric of the city. The analysis of the evolution of city planning shows that projects have failed to break this logic. The delay accumulated in this field since the 80s had the effect of amplifying the phenomenon. Furthermore, this duality is reflected in the urban power struggle between the authorities and the inhabitants. On the one hand, the authorities seem determined to reproduce and keep constant both tension with and distance to the population, seeking to maintain their social control over the population. On the other hand, residents of poor neighborhoods regularly claim a "right to the city". This inertia does not mean a lack of change. This manifests itself through urban crises which temporarily break the balance. A new order is then implemented, replicating the urbanization process that prevailed in the old order. In a second phase, this research highlights the struggle for territory which emerges in these African cities. Indeed, in the midst of the general trend of inertia and reproduction, a few evolutions are worth mentioning. There is first of all a real spatial and social fragmentation of urban areas. This process occurs both in the slums and the formal rich neighborhoods mushrooming more and more on the outskirts of the city (near the urban ring roads serving these new places in which to live). To this diversification of territorial situations can be added an increasing number of slum upgrading projects, the results of which fail to meet the original targets. Moreover, even within neighborhoods, there is a fragmentation of community spaces, such as markets. The latter have undergone an important evolution since the 80s, sometimes leading to conflict between this type of local trade and the business carried out in shopping malls, which is claimed to be modern. The influence of the space of flows and the implementation planning process promote liberal "modern" sector, consisting of subsidiaries of large corporations, supermarket chains to a upper class people, while causing profound changes in space with neighborhood markets. The challenge of planning for the city of tomorrow appears to reduce this duality and to take into account this duality to prevent the development of precarious neighborhoods and urban fragmentation.

EPFL2012

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

Concevoir à grande échelle

Mathieu Louis Pierre Mercuriali

Large-scale design - Mobility interface models and urban transformation strategies This research project is based on the hypothesis that the urban transformations generated by mobility interfaces constitute a key component of successful sustainable urban development. Effectively visioning and understanding these multimodal interchange hubs must therefore become a major strategic objective, in order to conceive an urban model that is compact - and networked and intelligent. With this aim in mind, this research aims to propose innovative strategies for transforming these communication interfaces into central reference points within the contemporary metropolitan landscape. Projects of this kind have already been designed and realised in most major European cities during the second half of the 20th century. These designs, characterised by their complexity and scale, formed the starting point of the major railway stations in today's cities, incorporating different forms of mobility over the course of time. Today they appear not just detached from their urban contexts - the very contexts in which they are embedded - but also unable to meet the current demand for functional mixity and communication effectively. They are undergoing obsolescence and finding it difficult to adapt to the paradigm shifts that have intervened - socially, economically and spatially. At a time when the city can no longer be conceived exclusively in terms of ex-nihilo construction, but must be viewed in terms of transforming an existing built fabric, what future can be proposed for these existing transport interfaces? What strategies can be developed to anchor them in their surrounding urban context? What capacity do they have for hosting new activities, new public and private spaces? Finally, what forms is it possible to imagine for this kind of design? Three hypotheses emerge: the development of mobility interfaces has generated specific architectural and urban forms correlating to the evolution of mobility forms themselves; the transformation and obsolescence phases of mobility interfaces offer potentials for metropolitan regeneration; and the process of producing a complex design calls for articulation and interrelation between different architectural and urban scales. To verify these hypotheses, the first part of this thesis is focused on the comprehension and analysis of these multimodal hubs, based on a review of architectural and urban theories that address the issue of how major urban projects relate to transport infrastructures. This is followed by close analysis of a series of relevant case studies within the Paris metropolitan area. The second part of the thesis proposes design tools to generate new urban and architectural design processes, derived from a process of design-based research. The final part of the thesis aims to demonstrate that this type of intervention is a design project with its own specific scale and complexity: between large building and urban fragment.

EPFL2015