What’s happening with suburban jobs in Melbourne?

Density of employment in Melbourne, 2006, in one km wide circular bands by distance from CBD (jobs/km2)

The first exhibit shows the popular view of the geography of urban employment in Australia’s largest cities. It is commonly assumed the great bulk of jobs – and certainly virtually all “good” jobs – is located in the CBD.

This is an understandable view given the first exhibit shows the spatial distribution of employment density in Melbourne in 2006. It indicates the density of jobs in the Central Business District (CBD) – the first one km radius ring around the town hall – is an order of magnitude higher than anywhere else in the metropolitan area. It closely aligns with the cluster of high rise office buildings that define the CBD in the popular imagination.

Share of metropolitan employment in Melbourne in one km wide circular bands by distance from CBD, 2006 (%)

But is this is an adequate representation of the geography of employment in Australia’s second largest city? The second exhibit highlights that density is not the same as the number of jobs. It shows how employment is really distributed within Melbourne – the CBD is easily the largest single concentration of employment, but it nevertheless has only 15% of all metropolitan jobs. In fact only 28% of metropolitan jobs are located in the inner city – i.e. lie within a 5 km radius of the town hall – and 50% are located within 13 km radius.

This dispersed pattern is not recent. Melbourne was compact and dense up until the end of the nineteenth century when the appearance of mechanised transport – primarily trams and trains – enabled middle class residents to escape the crowding and congestion of the centre for the space and amenity of the suburbs. This trend was boosted dramatically after WW2 when increasingly widespread car ownership democratised access to affordable land on the urban fringe.

Firms followed a similar pattern. Initially, manufacturing and distribution firms moved to the outer suburbs so they could escape congestion in the inner city, exploit new space-intensive horizontal production methods, and be closer to the suburbanising workforce. The suburban population generated increasing numbers of jobs to service its consumption needs, amplified by the increasing level of outsourcing from the home. More recently, some higher order activities have moved from the CBD to near-CBD and inner city locations and some back office functions have moved to the suburbs.

By 1981, only 35% of Melbourne’s jobs were located within 5 km of the centre. The “average job” was 12.4 km from the centre and the “centre of mass” of employment was 5.9 km away. The trend to the suburbs was very strong over the succeeding 25 years. By 2006 just 28% of jobs were within 5 km radius and the ‘average job’ was now 15.6 km from the centre. The centre of mass had moved 2 km further outwards to the vicinity of Tooronga, 7.9 km from the CBD. Read the rest of this entry »


Are infrastructure costs higher on the fringe?

Capital costs per dwelling of infrastructure provision - inner suburbs vs outer suburbs (from Trubka et al)

The exhibit above purports to show that the cost of infrastructure associated with building a new dwelling within 10 km of the CBD of a city like Melbourne is, on average, $50,503. In contrast, it costs $136,401 to provide infrastructure for an outer suburban dwelling i.e. located more than 40 km from the CBD. That’s a huge difference: $85,538 per dwelling.

The figures come from a 2007 report, Assessing the costs of alternative development paths in Australian cities, written by three Curtin University academics, Roman Trubka, Peter Newman and Darren Bilsborough. I’ve mentioned this report before, but that was primarily in the context of The Age and some public sector agencies tending to conflate economic costs with infrastructure outlays (they’re not the same!).

The figures above however are solely infrastructure outlays (not economic costs). Judging by the extent to which Trubka et al’s report is cited by government agencies, there appears to be strong demand for this type of information. It seems, however, that these are the only numbers on this topic around. That’s unfortunate because they have some very serious shortcomings as an indicator of the relative cost of providing infrastructure in inner and outer locations.

The key deficiencies are they’re old; they don’t relate to Melbourne; and they’re not transparent. Trubka et al sourced them from a 2001 report, Future Perth, prepared by the WA Planning Commission to assess infrastructure costs in Perth. Future Perth didn’t calculate its estimates from first principles but rather surveyed 22 earlier studies, some dating from as far back as 1972 and some relating to costs in the USA and Canada.

Future Perth is a working paper and hasn’t been published – hence the rigour of its methodology and those of the 22 studies it drew from hasn’t been tested. Unfortunately, Trubka et al provide scant explanation of their infrastructure estimates, relying instead on a reference to Future Perth.

I can’t say for sure the Trubka et al estimates are wrong, but I can say they’re unlikely to be right. I can also say they’re far too flaky to be relied upon to guide significant policy or investment decisions here in Melbourne. There’s clearly a demand for this sort of information so it would be sensible for the State Government to undertake its own rigorous and up-to-date assessment of the costs of metropolitan infrastructure provision.

Although not as decisive as the shortcomings discussed above, I also have some issues with how Trubka et al have set up their cost comparison. Actually, because the report doesn’t elaborate much on the various infrastructure items, I’ll treat these as questions, or areas that need clarification. Read the rest of this entry »


Is Melbourne pushing the boundary (too far)?

Melbourne in 1988 - a part of the 2010 image, showing the effects of the drought, is visible on the RHS

Geosciences Australia has released a new series of satellite images comparing the extent of development in Melbourne in 1988 with 2010. Click on the image above to go to Geosciences Australia’s web site where you can do a “swipe” comparison of the two images i.e. move the cursor across the image to progressively reveal the second image underneath.

According to a report in The Age, the images show a “massive” increase in urban sprawl, with Melbourne’s urban footprint surging to the north, west and south-east. Melbourne has “marched into surrounding rural landscapes” and its “unofficial boundary is now more than 150 km east to west”.

Melbourne has certainly expanded at the fringe over the last 22 years, there’s no doubt about that. However I’ve argued before that both the extent of sprawl and its downsides are routinely exaggerated, so I want to have a closer look at these images and at The Age’s interpretation.

One thing that struck me straight up is that any comparison of the two satellite images can be misleading unless the viewer appreciates Melbourne was still suffering the effects of a long drought in 2010 (compare the size of the dams in each year). So areas that appear to have gone from green to brown between 1988 and 2010 might reflect lack of rain, rather than an increase in development.

In fact 1988 was an unusual year. There was a La Nina event in 1988-89 – the first since 1973-76 – and hence there were wetter than normal conditions. Have a look at this older CSIRO comparison of satellite images of Melbourne in 1972 and 1988, and note the CSIRO cautions that 1972 was much drier than 1988.

It should also be borne in mind that 22 years is a reasonably long period in urban development terms. We shouldn’t be surprised to see substantial change when a metropolitan area is growing. Have a look at these images to see how spectacularly some other growing cities have changed in the course of 20 years.

The level of growth also needs to be considered. Melbourne’s population grew from circa 3.1 million to around 4 million between 1988 and 2010. That’s an increase of about 30%, which is considerably more than the apparent increase in the size of the urbanised area. That’s to be expected, as a large proportion of population growth – currently approaching half – is accommodated within the existing urban fabric via redevelopment.

And then there’s The Age’s claim that Melbourne’s urban footprint spreads “more than 150 km east to west”. It doesn’t. Using GIS, I measure at most 75 km from the western edge of Wyndham to Lilydale in the east and 85 km to Pakenham in the south-east. If I measure instead from Melton (putting aside that it’s separated by 9 km of green wedge from the continuously urbanised area), I still get less than 80 km to Lilydale and less than 100 km to Pakenham. Some might think that’s still too big, but it’s a lot less than 150 km plus. Read the rest of this entry »


Is inner city living the solution to obesity?

How much exercise is needed to burn off food?

It’s often pointed out that residents of the inner city, on average, are less obese than residents of the outer suburbs. Since the inner city is denser, more walkable and has much better public transport access than any other part of the metropolitan area, the conclusion seems obvious to many – a key strategy to address obesity should be to encourage higher dwelling densities and better public transport in the suburbs, especially the newer, fringe areas.

The flaw in this thinking is it fails to observe that the inner city – defined roughly as the area within 5 km of the CBD – is a different world. Relative to the suburbs, the inner city has an emphatic over-representation of younger, well educated and affluent residents with fewer dependents. The proportion of the population made up of young singles is three times that of the metropolitan area as a whole and there are twice as many young couples without children.

These are the sorts of people who on average are slimmer because they’re younger, who are of an age where appearance is enormously important, and who are well educated enough to know about nutrition and eschew fast food. They can afford to buy high quality fruit and vegetables and pay for gym memberships. Because they’re more affluent, they have fewer children on average and hence less need for a car.

They live in smaller dwellings so they can be near the CBD and take advantage of its enormous and unparalleled concentration of high-paying professional jobs, its matchless endowment of cultural attractions and its huge and diverse range of social and entertainment opportunities. There’s no other concentration of activity within the metropolitan area that comes even close to the richness of what the inner city offers.

Because they live at higher density, driving is too hard for many trips – roads are congested and parking costs range from expensive to impossible. So residents often walk or use public transport instead. That’s O.K., because they happen to live in that transit-rich, small and unique geographical area where every train line and tram line in the entire metropolitan area – the result of 130 years of construction and at least one spectacular land boom – converges.

So population density and access to public transport are not the underlying forces driving this group’s superior average BMI. Rather, it’s a combination of the small but highly specialised group who can afford to live there, on the one hand, and the special characteristics of the area, particularly the presence of the CBD, on the other.

It’s pie in the sky to imagine the sheer scale and complexity of the highly specialised attributes offered by the inner city could be replicated in the suburbs – much less the outer suburbs – within the foreseeable future. The inner city is focussed on the CBD and in almost every city in the world, the number of jobs in the city centre is an order of magnitude larger than any suburban centre (Atlanta is possibly the sole exception). In Australia, the centre offers the cream of corporate jobs.

The importance of proximity to the CBD in explaining the special character of the inner city is demonstrated by the fact walking’s share of work trips plummets from 13% in the inner city to just 2% immediately one locates in the adjacent inner suburbs. This share is only marginally better than the outer suburbs.

Will building at higher densities and providing better public transport in the outer suburbs significantly lower the incidence of obesity? Not likely. Even if all outer suburban dwellings were townhouses, the incentive to walk is much lower if there’s no CBD, cultural precinct, river, beach, historic buildings, hundreds of cafes, and hundreds of thousands of jobs to walk to. Perhaps most importantly, the outer suburbs don’t have the constraints on driving and parking that often make walking or public transport a superior alternative in the inner city. Read the rest of this entry »


Where is Melbourne’s ‘centre of gravity’ ?

Change in the 'centre of mass' of employment in Melbourne, 1981-2006

We’re familiar enough with the idea of the ‘centre of gravity’ of population in Melbourne. But where is the centre of gravity of employment?

Is it the city centre? No, for one thing the CBD’s only got around 15% of all metropolitan jobs. For another, the combination of Melbourne’s distinctly lop-sided growth south of the Yarra and the fact that 72% of jobs are more than 5 km from the CBD, suggests it’s going to be somewhere south east of the CBD.

So I’ve calculated the location of the centre of gravity (more correctly, the ‘centre of mass’) of jobs from Census data. The accompanying chart shows how that location changed over the period from 1981 to 2006.

The centre of gravity is calculated by dividing Melbourne up into 1,000 traffic zones and weighting the coordinates of the centroid of each zone by the number of jobs it holds. If you imagine a relief model of employment in Melbourne, the centre of gravity is where you’d rest the model on a needle so that it balancess perfectly.

In 1981, the centre of mass of employment was 5.9 km east south east of the CBD, on Kooyong Rd, just north of Toorak Rd. By 2006 it was 7.9 km from the CBD, close to the corner of Malvern and Tooronga Rds.

This movement reflected the much stronger growth in jobs in the suburbs over this period compared to the CBD and inner city. Read the rest of this entry »


Will networking make public transport the mode of choice?

What's the biggest danger?

According to a report in The Age last month, new research published in the latest issue of Australian Planner shows that higher suburban densities are not a precondition for vastly better public transport. Reporter Andrew West says:

City dwellers have been presented with a false choice – live in apartments and enjoy good public transport or retain the house and land and rely on cars

The research by Dr John Stone and Dr Paul Mees contends that it is not necessary to intensify land-use across the whole city before significant improvement in both patronage and economic efficiency of public transport becomes possible.

They say the contribution made by urban consolidation “to recent public transport patronage growth is modest and makes little impact on the density of the whole urban region”. Most residents of Australian cities will continue to live in houses and suburban subdivisions that are already built so “alternatives to the car will need to be effective at existing urban residential densities”.

They argue instead for a ‘networked’ model of public transport. Improving the way existing public transport resources are managed – especially by providing higher frequencies and improving coordination between services and between modes – will yield significantly higher transit patronage in the suburbs without the need for broadbrush increases in density.

I’ve argued before that increasing residential density, by itself, will not necessarily increase public transport patronage significantly, much less shift travellers out of their cars in large numbers.

I’ve also argued that there are generally better gains to be had from using existing resources more efficiently rather than relying on strategies based around huge new infrastructure investments or massive land use changes.

And I think the idea of networking public transport is absolutely critical. By embracing transfers, networking provides faster travel paths to all parts of the metropolitan area than is possible by radial routing.

However it’s not obvious to me that ‘networked’ public transport, by itself, would have the sort of major impact on mode share in the suburbs implied by The Age’s report. I can see that it would make public transport much better for existing users and I’ve no doubt it would increase patronage, but I’m not persuaded that it would be enough to address the ‘false choice’ that The Age says Melburnites have been presented with. Read the rest of this entry »


Are the suburbs like the inner city?

Shweeb human-powered monorail - winner of Google's $1 million 10^100 environment project. Google chose Shweeb because of its transit potential, but there seem to be a few obvious questions they didn't ask!

Australian suburbs are commonly thought of as low density, single-use dormitories offering residents spacious lots, detached houses, quiet streets and a good measure of “leafy” amenity. Since it is assumed residents commute to the city centre, the suburbs are unsullied by the noise and grind of daily commerce.

It’s also commonly implied that the suburbs are homogeneous, alienating and unauthentic. As Graeme Davison says, suburbanites have variously been accused of conformity, philistinism, apathy and wowserism.

But it seems this stereotype is outdated. Housing densities are rising in the suburbs, whether through large developments like this 13 storey, 520 unit development on a redundant government site at Coburg in Melbourne (10 km from the CBD), or via numerous dual occupancy and small-scale infill town house developments in middle ring suburbs and the older parts of outer suburbs. Read the rest of this entry »