The urban structural unit: towards a descriptive framework to support urban analysis and planning

Abstract

At the most fundamental level, a city represents a set of structured relationships between space, form and flows. This paper focuses on the description of urban space and form to propose a classification framework to support subsequent explanation and interpretation of the flows of materials, energy and information which characterize the city. Description of urban form in terms of type, number and arrangement of parts and part-to-part relations, rather than explanation in terms of land use or historical derivation, is identified as the basis for decomposition of an urban space into a set of relatively morphologically homogeneous entities, or urban structural units (USUs). To enable a rigorous definition of the USU, this paper introduces the notion of a parallel hierarchy of open space, complementary techniques derived from space syntax to describe the urban street network, and consideration of other civil infrastructure networks (water, electricity etc.). Land classification systems are examined to assess the role of geophysical properties in delineating USUs. These diverse elements are combined into an integrated classification framework with the potential to support urban analysis, planning and design across multiple scales of investigation.