A Strategic Planning and Policy Decision Support Tool for Urban Regions

In this paper we present a Decision Support System developed to assist urban designers, planners and policy makers to explore and evaluate possible urban layouts and their growth patterns. Thecore of the system consists of a modelling shell allowing the user to specify cellular automata based models of urban and regional systems. These models capture the effect of local spatial processes in which the use, or desired use of each parcel or cell of land is determined partly by institutional and environmental factors, and partly by the activities present in its neighbourhood. Since each cell affects every other cell within its neighbourhood, a complex dynamic emerges. Unlike conventional cellular automata, the models are defined with a large neighbourhood --over a hundred cells-- a relatively large number of states --more than a dozen in some applications-- representing socio-economic and natural land-uses. The approach permits the straightforward integration of detailed physical, environmental, and institutional constraints, as well as including the effects of the transportation and communication infrastructure. These models thus permit a very detailed representation of evolving spatial systems. The current version of the system represents urban areas as consisting of up to 10.000 interacting zones, each roughly the size of an individual city block. These models are easy to build and apply, yet empirical tests show that they produce realistic simulations of urban land use dynamics. Consequently, they are well suited to form the heart of the DSS, which provides the user with a number of tools for exploration,analysis and evaluation of alternative futures of the system as they result from policy interventions that are imposed by means of what-if experiments and scenario analysis. For example, the DSS isable to identify areas in which pressure for change in land use restrictions may become critical under particular development strategies. In the DSS, the modelling shell is coupled to a simple,custom-built GIS. In the stand-alone application of the DSS, this stores the detailed geographical qualities of the area being modelled, and allows basic overlay manipulations. It also displays theresults of the model while the simulation proceeds. Alternatively, the GIS can serve as aninterface to more elaborate, commercial GIS systems