Infrastructure works not so much to propose specific buildings on given sites, but to construct the site itself. Although static in and of themselves, infrastructures organize and manage complex systems of flow, movement and exchange. Infrastructures are flexible and anticipatory. By specifying what must be fixed and what is subject to change, infrastructural design can be architecturally precise yet programmatically open. Instead of progressing toward a predetermined state (as with master planning strategies), infrastructure provides a framework for evolution within a loose envelope of constraints. An infrastructural approach establishes a directed field, where different architects and designers can contribute, but it sets technical and instrumental limits to their work. Lastly, infrastructures allow detailed design of typical elements or repetitive structures, facilitating an architectural approach to urbanism.