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RESEARCH PRODUCT

The Fractalopolis model - a sustainable approach for a central place system

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Controlling urban sprawl is nowadays considered as a most important issue of urban and regional planning. Indeed uncontrolled sprawl generates car traffic flows and lengthens the trip length for acceding to jobs or urban amenities concentrated in centers. Moreover natural areas are weakened by diffuse urbanization. Different models are discussed about how this evolution could be stopped. However simply coming back to monocentric big urban centers do not correspond to a peculiar type of social demand which aspires to a quiet and green environment. Hence, not taking into account such real demand, risks generating again migration flows to lower densely populated zones. Other more subtle concepts seem more realistic, as that of Northern European country city planning, based on green lanes entering into urbanized areas creating green amenities close to urbanized areas which are concentrated along public transportation axes. This holds, too, for New Urbanism. In the present we propose a planning concept based on the central place theory, but which modifies this approach by concentrating central places along public transportation axes. This allows reducing traffic flows by creating a great number of good accessible local centers offering daily needs, less important subcenters providing weekly amenities and a small number of high ranked centers concentrating rarely used amenities. The spatial system refferring to fractal geometry avoids cutting natural zones and preserves thus a large variety of contiguous habitats for animals. The concept allows, too, reflecting about population distribution and thus densities in such a system. A decision support system based on this approach allows developing and evaluating concrete planning scenarios.