Petrol poverty in Sydney

Some of my work got into the popular press recently, which is nice, because, afterall, urban planning/economics is meant to be an applied field. Here is a link to the article, (sans graphics I am afraid). The article got picked up by the peak oil crowd, and you can see a couple of different versions of the graphics here and here, for example, but, for convenience, I've put a scanned version of what appeared in the Sydney Morning Herald below.

Update: Paul Krugman picked this up from the Oil Drum, and stuck it on his blog. This is higher profile than I could've expected. I guess the lesson from this is that, if you want to get exposure, it really helps to gave some pretty/garish graphics....

Here is a low-res scan of the pictures that appeared in the paper(they have been tarted up by the paper, who did a nice job on them, but they are based on maps I produced).

The graphs shows average proportion of gross household income spent on petrol (orange is > 6%, yellow 4-6%, green 2-4%, light blue 1-2%, blue < 1%). Left is with petrol at $1.5 per litre, right is with petrol at $2 per litre (assuming zero price elasticity, just to keep things simple).

A few things to note:

Firstly, because these graphs show averages, they mask a lot of variation at the household level. Some individual households in the orange zone, for example, will be spending a lot more than 6% on fuel, which others will be spending a lot less.

Secondly, these costs are petrol costs only, not vehicle purchase/depreciation, rego, tolls, or other running costs. I took a quick squiz at the latest ABS data (2004 Household Expenditure Survey) which suggests fuel costs to be roughly a third to a quarter of total running costs for cars, on average. With fuel prices up, this proportion is probably a bit out of date, and is also likely to be an underestimate for those in the outer suburbs. Nevertheless, we might expect at least an average of perhaps 15% of gross household income on car travel costs for those in the outer areas, with some households much higher. These sorts of numbers are starting to get pretty significant, and make me think that the housing affordability people should start factoring in transport costs to their measures of affordability. Even if houses on the fringe in Sydney were cheap (which they're not), the extra costs of vehicle purchase and running would make them less affordable, if they were factored in.

The graphs were compiled using a travel model calibrated on NSW Department of Transport Household Travel Survey (3000 households annually across Sydney), so thanks to them. This travel model was applied to the 2006 Census data to work out the graphs you see here. I assume 9 litres per 100km fuel efficiency, because I dont have detailed information about the spatial distribution of the vehicle fleet in Sydney.

Here are the base images I provided to the paper. They're not as pretty as the ones in the paper, unfortunately.