Trading Zones and Public Spaces Transformations the Case of Piazza Leonardo in Milan

Starting from a real urban transformation experience related to the need to give a new life to Leonardo da Vinci Square in Milan, the paper explores the “trading zones” activated in this case where the design action is characterized by the absence of any institutional framework or mandate. In relation to such a condition, the authors discuss the nature of the design process and analyse the relevance of low structured scenarios as frameworks for activating a quasi-coordination context towards a more sustainable transformation of the square. Two main concepts are analysed: low structured scenarios as drivers (or boundary objects) for the “trading zones” enabling planning mechanisms to be created in coherence with existing forces and resources; dynamics of coordination, intended as an emerging property of decision systems when they operate within trading zones.The paper starts introducing the conceptual interplay between trading zones and the planning of urban, public spaces transformations.In the second part it discusses the two concepts within their specific literature domain so creating the operational framework for the description of the Leonardo da Vinci Square experience. This is then described by mapping along the time line the system of boundary objects keeping in life the specific trading zone. Each step is also analysed considering the specific coordination and alignment occurred among resources and actors. In particular, each step has been conceived, and/or considered, as an experiment characterized by specific conditions of governance, leadership, formal elements that this article uses as descriptors of the coordination dynamics. Finally some conclusions are discussed and some future research paths identified.