A THEORY ABOUT THE CITY AS OBJECT
01. February 2012
A series of recent papers (Hillier et al, 1993; Hillier, 1996b, 2000) have outlined a generic process by which spatial configurations, through their effect on movement, first shape, and then are shaped by, land-use patterns and densities. The aim of this paper is to make the spatial dimension of this process more precise. The paper begins by examining a large number of axial maps, and finds that although there are strong cultural variations in different regions of the world, there are also powerful invariants. The problem is to understand how both cultural variations and invariants can arise from the spatial processes that generate cities. The answer proposed is that socio-cultural factors generate the differences by imposing a certain local geometry on the local construction of settlement space, while micro-economic factors, coming more and more into play as the settlement expands, generate the invariants.
The ‘urban grid’, in the sense used in this paper, is the pattern of public space
linking the buildings of a settlement, regardless of its degree of geometric regularity.
The ‘structure’ of a grid is the pattern brought to light by expressing the grid
as an axial map1 and analysing it configurationally. A series of recent papers
have proposed a strong role for urban grids in creating the living city.
The argument centres around the relation between the urban grid and movement.
In ‘Natural movement’ (Hillier et al, 1993), it was shown that the structure of
the urban grid has independent and systematic effects on movement patterns, which
could be captured by ‘integration’ analysis of the axial map2. In ‘Cities as movement
economies’ (Hillier, 1996b) it was shown that natural movement – and so ultimately
the urban grid itself – impacted on land-use patterns by attracting movement-seeking
uses such as retail to locations with high natural movement, and sending non-movement-seeking
uses such as residence to low natural movement locations.
The attracted uses then attracted more movement to the high movement locations,
and this in turn attracted further uses, creating a spiral of multiplier effects
and resulting in an urban pattern of dense mixed use areas set against a background
of more homogeneous, mainly residential development. In ‘Centrality as a process’
(Hillier, 2000), it was then shown that these processes not only responded to
well-defined configurational properties of the urban grid, but also initiated
changes in it by adapting the ‘local grid conditions’ in the mixed movement areas
in the direction of greater local intensification and ‘metric integration’ through
smaller scale blocks and more trip-efficient, permeable structures.
Download the full article here, written by Bill Hillier, Space Syntax Ltd.