For an interaction between the scales of large urban plans and development projects, this paper explores the potential of exploratory design as a method. In order to address the morphological features of a project, the authors stress the importance of a graphical design tool - the abacus of guidelines - able to integrate all those variables that the complexity of the context embraces. The abacus is a graphical tool that sets a matrix of spatial invariants for the project according to a qualitative point of view and not only quantitative. This paper reviews some Italian examples developed between the 1980s and the 1990s, when a changed perspective on morphology and typology brought to design innovations. The paper tries to demonstrate that urban design, besides normative coding, can be supported by a graphic tool concerning the control of space physical configuration.
Keywords: Urban design; abacus; guidelines