The emergence of leapfrogging in an urban growth model combining and economic approach and cellular automata

S-ghost city : self-generating housing, open space and transportation in the city

International audience; S-GHOST city is a theoretical simulation model aimed at investigating the spatial patterns of urban growth. A gridded (cellular) 2D space is considered, with a CBD located at a crossroad. Households arrive sequentially in the city and choose their location by maximizing a utility function subject to a budget constraint. Households have preference for open-space and for the public goods that are located in their neighbourhood. They bear a cost for commuting to the CBD along the road network. As households migrate into this growing city, agricultural plots are converted to residential use, and the public authorities create a continuous network of roads so as to provide…

Transition phases and leapfrogging in urban sprawl patterns : a simulation and analytical approach with SGHOST

International audience

Collective and Cooperative Behaviour Models

International audience; In modelling residential choice we cannot escape the debate about the effect of societal context on an individual’s decision-making. This debate depends on whether we set more store by the aggregate scale of society or by the individual’s decision-making. An individual-centred approach will focus on the particularities of an individual and the way her past, for example, influences her decisions.

S-GHOST : un modèle d'auto-organisation de l'étalement urbain et du réseau de transport

S-ghost city : self-generating housing, open space and transportation in a city

International audience

Aménités urbaines et périurbaines dans une aire métropolitaine de forme fractale

In the THÜNEN tradition, Urban Economy is a striking abstraction, giving models that keep the main features of the wide diversity of real word cities. Nevertheless, this paradigm less suits the modern urban spatial structures (polycentrism, weak centripetal forces, etc.), particularly the peri-urban form of metropolitan areas, which are an urban/rural integrated space. In this paper, we propose a classical micro-economic urban model combined with a " SIERPINSKI's carpet " geometry, a fractal form which suits for fit together urban and rural areas in a hierarchical structure. Subject to a budget constraint, a household maximises a Cobb-Douglas/CES function, where household's taste for divers…

Emergence of scattered and leapfrog urban development : from analytical proof to complex simulation outputs with realistic calibration

International audience

How neighborhood forms impact urban development

International audience

How green neighbourhoods make cities more compact?t? A 2D microeconomic perspective

National audience; We analyse the emergence of scattered residential development, a key characteristic of sprawl. We analyse a 2D urban economic model with neighbourhood interactions among households (social contacts) and with farmers (who produce green amenities). Starting from a cross-shaped road network and CBD, we analytically establish the existence and characteristics of residential leapfrogging that breaks up the compact development of the city. We extend our analysis by numerical experiments based on observed or econometrically estimated parameters. We nd that the shape of built up areas in uences the decision or not to jump over undeveoped land or to stick to the contiguous urban f…

Aménités urbaines et rurales dans une aire métropolitaine de forme fractale

International audience; L’Économie Urbaine à la THÜNEN est une abstraction remarquable : la famille de modèles qui la constitue conserve des traits essentiels de l’infinie complexité des villes réelles. Cependant, elle est moins adaptée aux formes urbaines modernes (polycentrisme, relâchement des forces centripètes, etc.), en particulier au périurbain, en tant qu’il est un espace mixte. Cela nous conduit à proposer un modèle où l’on garde un programme microéconomique classique d’économie urbaine, mais qui fonctionne dans la géométrie d’un tapis de SIERPINSKI, fractale qui permet de styliser un emboîtement hiérarchique de zones rurales et de centres urbains dans une aire métropolitaine. Un m…

Morphological similarities between DBM and an economic geography model of city growth (Lecture notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 4)

International audience; An urban microeconomic model of households evolving in a 2D cellular automata allows to simulate the growth of a metropolitan area where land is devoted to housing, road network and agricultural/green areas. This system is self-organised: based on individualistic decisions of economic agents who compete on the land market, the model generates a metropolitan area with houses, roads, and agriculture. Several simulation are performed. The results show strong similarities with physical Dieletric breackdown models (DBM). In particular, phase transitions in the urban morphology occur when a control parameter reaches critical values. Population density in our model and the …

How neighbourhood interactions influence urban sprawl

International audience

Where Alonso meets Sierpinski: an urban economic model of a fractal metropolitan area

International audience; La coexistence d'activités résidentielles et agricoles dans des ceintures périurbaines caractérise de nombreuses aires métropolitaines modernes. Malheureusement, peu de modèles théoriques de l'économie urbaine prennent en compte ce type de mixité spatiale. L'article contribue à combler cette lacune : les auteurs présentent un modèle de localisation résidentielle (standard en économie urbaine) opérant dans un espace structuré par la géométrie spatiale. Plus précisément, d'un côté, un tapis de Sierpinski est utilisé pour rendre compte de l'organisation hiérarchisée de sites urbains et ruraux dans une aire métropolitaine. D'un autre côté, un ménage maximise, sous contra…

Modéliser la ville

Ouvrage publié avec le soutien de la Direction de la recherche et de l'innovation (service de la recherche) du Commissariat général au développement durable (ministère de l'Écologie, de l'Énergie, du Développement durable et de la Mer), en liaison avec le Programme de recherche et d'innovation dans les transports terrestres - PREDIT 4; National audience; Pour de nombreux acteurs, impliqués professionnellement ou politiquement dans les problématiques de la ville et de son aménagement, il est devenu clair que la planification de l’urbanisation ne peut être déconnectée des politiques de transport : elles interagissent l’une sur l’autre et doivent être considérées ensemble, ce qui nécessite de …

Dielectric breakdown and urban growth

Modèles de comportements collectifs et coopératifs

Le choix résidentiel est considéré comme un acte individuel ou celui d'un " mini-groupe " (famille) qui est conditionné par des références collectives. De ce fait, il s'appuie sur des informations (renommée de quartiers, d'une école, accessibilité à des services, commerces ...) mais il contribue également à l'émergence de tendances (préférence de certains modes de vie et de quartiers ...) qui peuvent être à l'origine de flux migratoires. Ces derniers participent à l'émergence de nouvelles configurations spatiales à l'échelle d'une ville, donc de phénomènes macroscopiques. De telles tendances sont donc le résultat d'interactions entre individus et groupe sociaux, entre individus et société, …

Morphological similarities between DBM and a microeconomic model of sprawl

JEL classification : C61; C63; D62; R21; R40; International audience; We present a model that simulates the growth of a metropolitan area on a 2D lattice. The model is dynamic and based on microeconomics. Households show preferences for nearby open spaces and neighbourhood density. They compete on the land market. They travel along a road network to access the CBD. A planner ensures the connectedness and maintenance of the road network. The spatial pattern of houses, green spaces and road network self-organises, emerging from agents individualistic decisions. We perform several simulations and vary residential preferences. Our results show morphologies and transition phases that are similar…

Morphological similarities between DBM and an economic geography model of city growth

International audience; An urban microeconomic model of households evolving in a 2Dcellular automata allows to simulate the growth of a metropolitan area whereland is devoted to housing, road network and agricultural/green areas. Thissystem is self-organised: based on individualistic decisions of economic agentswho compete on the land market, the model generates a metropolitan area withhouses, roads, and agriculture. Several simulation are performed. The resultsshow strong similarities with physical Dieletric breackdown models (DBM). Inparticular, phase transitions in the urban morphology occur when a controlparameter reaches critical values. Population density in our model and theelectric …