SUMMARY
The main difficulty in urban planning decision processes is that several aspects must be taken into account simultaneously, together with their consequences. The human mind alone is not able to manage and process all the information correctly or completely. Quantitative models are able to formalize problems and define evaluation functions, providing unbiased analyses focused on the important aspects of the decision. Operations Research models are able to solve complex systems of relations, with the additional possibility of optimizing an objective function. These models have demonstrated to be very useful in urban planning, where decisions must also pass through the delicate process of negotiation, which typically involves several decision makers with conflicting viewpoints. Using for example Mathematical Programming makes it possible a fast evaluation of the different decisions, as well as, of the relations, interactions, and consequences of the alternative decision choices. Sharing this kind of information helps the decision makers to cooperate and find a final common decision. Also transparency and traceability of the decision process are intrinsically guaranteed by the adoption of the formal method. In this paper we discuss this point starting from the origins of the ‘Strategic Analysis’ approach. Then we illustrate the model and the method which are implemented in STAN, a software recently developed to provide a useful operational tool for decision aid in urban planning processes.