Soudy 3: A Supply-Oriented Urban Dynamics Model with Innovation and Synergy Effects

Abstract

In the last few years a new family of evolutionary models of the urban hierarchy was presented (Camagni, Curti, Gibelli, 1985; Camagni, Diappi, Leonardi, 1986; Diappi and Pompili, 1987), whose main characteristics may be summarized in the following: i) The aim of linking together different theories and traditions in urban economics, which still remain mainly separated, such as the central place tradition, spatial interaction models, the reflections on ’optimal’ city size, the urban life-cycle model, the studies on urbanization and localization economies, intersectoral linkages and synergies in local development. ii) The aim of substituting the old-fashioned demand side approach, typical of the export base model and of most of part of land use and urban dynamics models, by a new supply-oriented approach; hence the acronym by which we define the new models: SOUDY, supplyoriented urban dynamics models. iii) The aim of integrating into the framework of urban models the truedynamic driving force of local development that, after Schumpeter, may be synthesized in the term ’innovation’. iv) The adoption of a methodology based on a ’master equation’ approach (Weidlich and Haag, 1982) — through which the probability distribution of the possible states of the urban system is defined at the macroscopic collective level, starting from the properties of the microscopic individual behaviour — and on the dynamic simulation of the growth process of each center of the urban hierarchy.