Epifania della liquidità urbana.

Density is nowadays the main character in the "liquid dimension" of the city; although it is apparently considered a simple tool, researchers and studies have rather recently explored its innovative, polysemic, ambiguous dimension, in order to interpret quantities and phenomena marking the anthropic space traversed by the fluid geometry of the complex and sometimes mysterious trajectories crossing contemporary metropolitan domain. In the process of refining useful knowledge for driving the city regeneration, density concept has to be re-interpreted according to new disciplinary coordinates. We can keep on using it by sketching and implementing predictive horizons based on a "static" dimension, but most of all it should be oriented to the "dynamic features" of the urban condition, an intricate entanglement of flows representing almost symbolically questions and contradictions of contemporary society. In the wake of what has been explored by the most advanced cultures of urban government at an international level, the density is progressing today to gain the core of urban policies, in Italy too. However, there is a widespread feeling that the huge innovative potential of such a tool, incredibly familiar to scholars and professionals, has not been explored enough. The maturity of the sustainability principles in urban policies, the substantial denial of monofunctional destinations and the revival of mixité, the development strategy often based on polycentric morphology, the raising demand for environmentally, friendly transport systems, more balanced modal share in metropolitan displacements and measures for densification related to transit, are all elements leading to investigate a new concept of density for catching and addressing the recent urban and metropolitan metamorphosis. In many circumstances density can represent the equilibrium axis for private-public relationships and the "desired" sustainability. Together with other "dynamic" indicators, as kinetics, connectivity and accessibility, flow density represents a crucial component for understanding and planning the “relationship domain" and the central places system of the “liquid city”, particularly emphasized by the "fourth dimension" of urban condition - the time factor - with significant implications on the strategic axes of the contemporary urban “vision”. Through conceptual excursions and significant case studies presented by international experts, the key issues of the book are developed exploring the progressive distance from the traditional, “static” density concept, as it can be argue in urban and metropolitan planning theory and practice in the last decades. The different forms of innovation, both in terms of integrated activity density and in the “dynamic dimension”, have been changing the development policy of the cities since the eighties and more and more in the last years. In contemporary urban management new signals and experiments, more or less explicitly, are pursuing the construction of a dynamic space through flow density and relationship intensity as incremental values of urban communities. The "new horizon" of planning may reveal itself in decoding the transformation phenomena of the city in terms of flows and relationship density, sort of dynamic coagulations with elastic geometry overcoming the static centralities of traditional urbanity, interacting in a dialectical way with the consolidated, identity space of the historical city.