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Box 11 Urban Density, Compactness and Urban Form
Greg Bamford
Views of the sustainability of cities often turn on claims about housing densities and overall
urban densities, which may seem to be relatively straightforward or independent matters of
fact. But how we measure densities depends on how we view cities so caution is needed.
If a city’s housing stock consists only or largely of low-density housing types, such as the de
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tached house and garden common in Australia, a low density city is the inevitable result. But
the use of higher density housing types (row houses, flats) can produce cities of any density,
from high to low, compact or sprawling. Much depends on the extent of open space, both
residential and non-residential, in the city and on its urban form.
Unlike the housing stock of Australian cities, that of Copenhagen and Stockholm consists
mostly of higher density housing types, yet these cities are not, correspondingly, such higher
density cities, because higher density housing types can be used to provide larger open spaces
adjacent to dwellings or residential areas, or to deliberately fragment a city without its overall
density plummeting.
Although these Scandinavian cities are often praised by compact city advocates they are better
understood as dispersed cities whose urban development is compact; they are modern ver
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sions of Ebenezer Howard’s Social City, a development of his famous Garden City.
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There is no
simple answer to how dense such cities are because of the extent and configuration of their
open space. Consequently, estimates of the density of Stockholm, for example, vary from one
half to several times that of Sydney.
The measurement of urban density is more problematic than one might at first suppose. Should
bodies of water in cities, in the form of rivers, lakes or harbours, be included in the density
calculation? What constitutes a gap in an urban fabric? When does an urban area stop being
urban and start being rural? As traditional differences between urban and rural settlement
patterns or communities change, how do we distinguish ‘urban’ from ‘rural’ or ‘peri-urban’?
In Howard’s Garden City, a rural or green belt, functionally integrated with the town it encircled,
was a means of preventing urban spread and the growth of conurbations. Is the density of the
Garden City only that of the town, or the town together with its rural belt of farms, woodland
etc. in which case its density is much lower? Howard’s spatially more complex ‘Social City’
brings this seemingly academic question to a practical head.
The Social City was to be an urban region, a necklace of six garden cities around a larger
‘Central City’ intended to carry the urban functions appropriate to a city of the size of the
Social City. The seven urban areas of the Social City would be inter-connected by transport
corridors but remain separated by wide and continuous rural or green space. The novel form
of the Social City would thus produce a density as low as that of any Australian city even though
the density of any of its component ‘cities’, which were quite compact, was several times higher.
In a nutshell, then, this is how the variations in estimates of the densities of Stockholm and
Copenhagen come about, because of their garden city lineage. We can’t decide what consti
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tutes the city in such cases.
Copenhagen nicely illustrates the problem of measuring urban densities without considering
urban or city form, and of identifying compactness with density. Rest the palm of your hand
flat on a table, with no gaps between your fingers. Then spread your fingers as widely as pos
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sible. This is a good approximation of the Copenhagen plan – your fingers are the post-war
growth corridors. Notice that your closed hand occupied the same area on the table as your
spread hand does. So, by analogy, urban density remains unchanged as your fingers spread (if
the space between them is discounted as rural) but the compactness of your hand decreases
as your fingers spread (or grow longer).
There is no simple equation of density or compactness with sustainability - much depends on
the uses to which open space can be put or the contributions it makes in cities, which these
widely admired Scandinavian cities amply demonstrate.
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