Would we use an airport train (as much as we say we would)?

Ground transport mode share for Melbourne Airport passengers (%) - data from Melbourne Airport

Yesterday’s post on the unreliability of predictions fits nicely with the latest round of calls for a rail line to the airport. The stimulus this time is a report in The Age last week on Melbourne Airport’s plans to upgrade freeway access and build a new terminal.

It set off a predictable and familiar landslide of calls for a train line. There were 141 comments on the article, virtually all of them advocating an airport train. I must say that I’ve hardly met a Melburnian who doesn’t think an airport train should be a high priority of any and all governments.

Some doubtless think others would use a train and thus, they imagine, reduce congestion on roads leading to the airport. But I expect most see themselves avoiding gridlock, punitive airport parking fees, or high taxi fares by using the train for most of their airport travel.

And yet if the train were built, there’s no doubt their prediction would prove to be enormously over-optimistic. Brisbane has a train from the CBD to the airport that carries just 5% of all travellers (another 3% come by bus). Sydney has a train too – it only carries 10% of all travellers (and a further 2% access the airport by bus). As Jarrett Walker observes, the political popularity of airport rail “is always several orders of magnitude above its actual ridership”.

Is there any reason to think that a train to Melbourne airport would increase public transport’s existing share of travel by a significantly greater amount than the trains have in these other cities?

Even without a train, Melbourne Airport already has a higher public transport mode share than either Sydney or Brisbane, with 14% of travellers accessing the terminal by bus. The former Government’s specification for a future airport train was a $16 fare, 20 minute trip time and 15 minute frequency. That’s much the same as SkyBus provides at present.

It’s true trains are generally more appealing than buses, but I can’t see that’s likely to lift public transport’s share significantly – certainly it hasn’t been enough in Brisbane and Sydney. It’s more likely it would cannibalise SkyBus and perhaps gain one or two additional percentage points of mode share.

If the latent demand for better public transport service between the airport and the CBD was as strong as readers of The Age think, then SkyBus – which offers the best frequencies and span of hours of any public transport service in Melbourne – should be doing much better than it is now (and it’s doing quite well).

It’s often argued that if an airport train were priced at a Zone 1-2 fare, it would attract higher patronage than SkyBus. That’s likely to be true, but it’s totally unrealistic – no Government is going to spend billions on an airport rail line and then subsidise its operations. And nor should it.

In any event, I doubt the increase in patronage would be anywhere near as dramatic as some assume. There is a host of reasons why the great majority of travellers would still prefer to drive or take a taxi than pay even a Zone 1-2 fare.

For example, most airport trips are to or from homes and workplaces in the suburbs – a taxi or a car is usually going to be more convenient than going to the local station and transferring to the airport service at Southern Cross. For many regular travellers, taxis and parking are cheap because they’re a business cost.

For tourists, it’s easy to justify a taxi for an occasional and important trip. Most tourists also travel with at least one other person, so in many cases that will improve the competitiveness of a taxi, or the long term car park, relative to public transport (I’ve elaborated on these reasons in previous posts – see Airports & aviation category in sidebar). Read the rest of this entry »


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 »


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 »


Should rail commuters pay a congestion toll?

Melbourne’s peak train services are overcrowded and have been for quite a few years. Given the high costs that peak period commuters impose on the rail system, wouldn’t it be more efficient and more equitable if they paid more for their tickets?

After all, the capacity of the system is determined by peak demand – all those trains and the associated infrastructure and personnel required to handle the peaks are under-utilised or sit idle for the rest of the day and on weekends.

Too crowded to get a seat?

As would be the case with congestion charging on roads, a charge on peak hour train travellers should reduce over-crowding (congestion) by suppressing travel, moving lower value trips to off-peak periods and encouraging shifts to other modes. Passengers who continued travelling in the peak would make a larger contribution towards what it actually costs to get them to work.

I’m prompted to think about this issue by a proposal to levy a $0.50 per trip surcharge on customers of Washington D.C.’s Metro system who use or pass through the network’s busiest stations during the busiest period of the peak. If approved, the congestion toll would apply from next month. Read the rest of this entry »


Is obesity really caused by suburban sprawl?

Suburban sprawl is often linked with rising obesity – for example, see this submission to last year’s Urban Growth Boundary Review from Kelvin Thompson, Labor Member for the Federal seat of Wills, or this article in the Sydney Morning Herald.

The customary argument is that because the incidence of obesity is lower in the inner city where densities are higher, it follows that low density outer suburban development is the cause, or at least a very significant contributor, to obesity.

At first glance this seems to make some sense. For example, only 1.1% of workers in Melbourne’s outer suburbs walk to work, compared to 12.9% in the inner city.

But for all its faults, is it reasonable to put the blame for obesity on sprawl?  No, it isn’t reasonable. We would we better off focusing our energies on the real issues associated with sprawl rather than being distracted by sideshows.

The key reason is that what goes in our mouths is more important than how much we exercise. You have to walk the dog for an hour and a half, or cycle for an hour, to burn off the calories in just one Big Mac.

The inner city has a lower incidence of obesity primarily because the residents eat better. And they don’t eat better because of higher density but because they have higher incomes than residents of the outer suburbs and, importantly, higher levels of education. They are more likely to know about the importance of good eating and they are more likely to be able to afford to eat better food. They also have smaller households on average so it’s easier to cook healthy food at home rather than go out for fast food. Read the rest of this entry »