Share of journeys to work by car, 2006 (click). Map from Charting Transport

The accompanying map from Charting Transport shows the proportion of journeys to work in Melbourne’s inner city undertaken by car in 2006 — the rest were by public transport, walking and cycling (note that green denotes a low share for cars and red a high share*).

There is a clearly defined area — the ‘golden mile’, bounded by Spring, Flinders, Spencer and La Trobe — where cars capture less than 30% of all journeys. Around Swanston Street the share of journeys taken by car is as low as 24% (click to enlarge map).

But the really striking thing to my mind is the steep increase in car’s mode share as soon as you move beyond walking distance of the rail loop. You only have to go as far as the northern side of Victoria Parade and that share jumps to 50– 60%. Go toward the Hoddle Street end and it’s more than 70%. Once you get into the suburbs, most employment concentrations have a mode split that is 80% – 90% car.

One interpretation of the data is that sustainable modes are doing pretty well in the golden mile. Another is that they’re not doing well enough – maybe no more than 10% of journeys should be considered the ‘natural’ share of the car in this sort of key business area – and hence there’s an opportunity for public transport to increase its share.

I incline to the latter view, but I think there’s another interpretation of this data that’s arguably more significant. Consider what it takes, in terms of density and transit supply, to get the share of journeys to work by car down below 30%.

The ‘golden mile’ is just 2 km2 out of a built up area of around 2,500 km2 (the entire MSD is over 7,500 km2). That little area is the largest single concentration of jobs, by far, in the metropolitan area. It accounts for 10% of all metropolitan employment and is denser by an order of magnitude than any other activity centre in Melbourne, as exemplified by the number of very tall buildings it contains. And despite its diminutive size, it’s the focus of the entire metropolitan train and tram systems. It’s the ‘hub’ where all the ‘spokes’ meet – a giant transport interchange – and is accordingly, again by an order of magnitude, the most accessible place in Melbourne by public transport.

Yet for all the astonishing advantages of job density and public transport quality, a quarter to a third of all those who work in this tiny area still drive to work. Further, literally within one or two blocks of the rail loop, the car’s share of journeys to work rises to 50% and more, notwithstanding that these near-CBD areas themselves have a job density and level of public transport service that is far higher than the rest of the metropolitan area. And this is the journey to work – the trip most likely to be taken by public transport!

I think there’s an incredibly important message here. Melbourne’s future can’t be planned on the assumption that providing more public transport is the primary policy answer, much less the only one. What this analysis says, in essence, is that any area that doesn’t look like the CBD will inevitably be served mostly by cars. However replicating the scale, density and infrastructure of the CBD elsewhere in the metropolitan area is extremely unlikely. There are only one or two other cities in the world (Atlanta is one) which have another job centre that rivals or exceeds its CBD in size.

Public transport in Melbourne will need to be improved and expanded on a scale not seen for generations in order to cope with projected growth. But even more attention needs to be given to how we can live successfully with the car. Travel by car needs to be made more sustainable, less congested and much more pleasant for residents and other road users. Peak oil and climate change should hasten this process but they won’t make cars obsolete and neither will politicians. Managing cars well will be the key transport challenge for Melbourne’s long term liveability.

* Map only shows mode split in zones where density >1,000 jobs/km2