Urban design with patterns and shape rules

The goal of an urban plan is to provide a development vision for a given territory. Three crucial issues in the conception and implementation of urban plans are how to define the program, how to convert the program into a flexible design, and how to adapt the design to changes in the program. This paper describes the preliminary results of ongoing research aimed at devising a methodology for addressing these issues. This methodology uses Alexander’s pattern language to define the program and Stiny ́s shape grammar formalism to convert the program into design solutions. A design studio has been used as the basis for developing and testing the methodology. Preliminary results suggest that the use of patterns helps to tie the urban plan to a specific development vision, and shape grammars are successful in generating alternative design solutions that match varying programs. Context Urban design is a complex activity that implies the participation of agents with conflicting interests. The impact is twofold. First, it raises communication difficulties due to the lack of a common language among such agents. Friedman has proposed the notion of development vision to refer to the set of somewhat general and abstract features underlying any urban plan. This should shift the focus of the discussion among urban planners from the specific layout formalization to concrete planning concepts as main generic goals. In practical terms, the development vision corresponds to a conceptual urban program. Designing vast urban spaces usually involves two long stages before a final implementation. First, the design process begins with the definition of an urban program and then converts it to a design layout. Second, the complexity of the large scale developments often implies a long term implementation throughout which changes in social and economic context may occur. Therefore, a mechanism to adapt the design to programmatic changes is also required. In this paper, we explore two formalisms to overcome the difficulties raised by the complexity of the urban design process. The first is Alexander’s pattern language and the second is Stiny’s shape grammar formalism. The pattern language is proposed as the language common to all urban design actors that can be used to define the urban program. Shape grammars are proposed as the means to generate alternative design solutions. To convert the program into designs it is suggested to use Duarte’s notion of a discursive grammar, although this aspect will not be covered in this paper. A discursive grammar is composed of a programming grammar which generates design briefs according to contextual data, a designing grammar encoding a design language or style and a set of heuristics to guide the generation towards a solution that matches the design brief.