Australia’s capital cities are remarkably similar in terms of population density; although they’ve been getting denser over the last 15 years, they’re all still mostly made up of vast tracts of suburbia with a density of 500-2,000 persons per sq km i.e. the orange areas in the exhibits. (1)
But they differ enormously in terms of the number of precincts where population densities are seriously high like they are in the older parts of many European cities. Sydney in particular is “another country” compared to the rest of the nation.
The differences are shown clearly by a new ABS project, Australian Population Grid 2011, that maps the population of the entire country at the 2011 Census using a regular one square kilometre grid.
The new measure is consistent with the idea of Population-Weighted Density, which I’ve discussed a number of times before. The virtue of this metric compared to simple average density is that it takes into account the way variations in density are distributed geographically. (2)
Sydney has 114 sq km with a density over 5,000 persons per sq km. In contrast, Melbourne only has 34 sq km and Brisbane has a mere 3 sq km. None of the other capitals have any. (3)
Sydney’s status as an outlier is reinforced when even denser areas are considered. There are 21 sq km in Sydney with a population higher than 8,000 persons; the densest square kilometre, which includes Potts Point and Woolloomooloo, has 15,000 residents.
Notwithstanding charges that Melbourne is turning into Hong Kong, there’s only one square kilometre of Melbourne that has a population higher than 8,000 (it’s in Carlton and has 10,500 residents). No other capital has a single one that exceeds this threshold.
The highest density grid cells in Melbourne are close to the city centre; however those in Sydney show much greater dispersal with some close to the boundary of the built-up area (see second exhibit).
Compared to London though, Sydney is definitely not an outlier. Almost 330 sq km of London has a population density in excess of 8,000; the densest one kilometre square cell has a population of 20,447. (4)
The reason Sydney is so much denser than Australia’s other major cities isn’t clear. It’s likely related to factors like its constrained geography and topology, the impact of infrastructure charging policies, the composition of its economy, its size, planning policy, and a range of specific historical factors (see Are Australian cities sprawling at ever-lower densities? for a discussion of the impact of developer charges on density in Sydney) .
- For the most part, grid cells with a population of less than 500 (the cream ones) aren’t generally regarded as part of the urbanised area
- I’ve looked at the merits of Population-Weighted Density a number of times before (e.g. see here, here, here and here ).
- Like all ABS spatial units, the grid system connects to all Census data and, as well, provides an indication of an area’s accessibility. Density though is only one indicator of an area; it doesn’t tell us about other factors like the mix of land uses in each cell or the urban design quality of a place. The densest cells might not be the most vibrant.
- The London map also shows the high proportion of the London population that lives in the “overspill” cities beyond the boundary of Greater London and commutes to the city.