Peak cars: Is our addiction ending?

In the 1980's it was dubbed "automobile dependency" – a term coined by Peter Newman and Jeff Kenworthy to describe the largely Western phenomenon of building cities around cars and thus cultivating a kind of addiction to them. But according to a new paper by Professors Newman and Kenworthy – part of the team at WA's Curtin University Sustainability Policy Institute – the West's car addiction could be meeting its demise; a relatively recent and unexpected phenomenon the professors are dubbing "peak car use."

"It's a bit like peak oil," Professor Newman told Robyn Williams on ABC Radio's The Science Show recently. "We are not noticing the big impacts yet but we have gone over the top. And that peak in car use per capita began in 2004 across the world. ...And US cities are now showing absolute declines in many cases, but the per capita peak happened in 2004 in Australian cities as well." In Sydney, Newman says, car use has not increased for five years.

But it's not that the car is disappearing, says Newman, it's more that it is "reaching its limits" in the major cities of the world. "That's the key message," Newman told Williams: "In many ways that is what is happening in these big megacities, they are grinding to a halt in their traffic. ...And most ...are now saying we've got to do something different."

That "something different" can be seen in the plans of Chinese and Indian cities which are both on a spree to build Metro rail projects across their cities. The metro in Shanghai alone carries eight million passengers a day, says Newman, and covers 80 per cent of the city.

But back to peak cars; The new paper by Newman and Kenworthy – ‘Peak Car Use’: Understanding the Demise of Automobile Dependence – says the trend was first picked up on in 2004, in a US study of per capita car use (Puentes and Tomer, 2009). A similar trend was then found in a study of Australian cities (Stanley and Barrett, 2010), in that the peak had come at a similar time (see chart below) and car use per capita has seemed to be trending down ever since.

So what's behind this "unexpected" development? According to Newman and Kenworthy, there are six possible causes of 'peak car use.' They are: 1. Hitting the Marchetti wall; 2. The growth of public transport; 3. The reversal of urban sprawl; 4. The aging of cities; 5. The growth of a culture of urbanism and; 6. The rise in fuel prices. Here's a brief summary of what the paper says on each of these:

1. Hitting the Marchetti wall

This relates to a phenomenon first recognised by Thomas Marchetti, that all cities have a similar average "travel time budget" of about one hour. That is, humans seem to be biologically programmed against taking more that one hour out of their day to get to work and back home again. Newman and Kenworthy have since applied this theory to city building, to show that cities always hit the wall when they are ‘one hour wide’. An 'Automobile City', says the paper, based on an average speed of 50 km/h, can reach out to 50km wide before the average travel time becomes more than what is acceptable to most people. But as cities have filled with cars and become increasingly prone to time-consuming traffic jams, even on highways, the Automobile City looks to be hitting the wall. Newman says high-speed rail is the only way to solve this. Hence China's plans invest up to 4 trillion yuan in high-speed rail between 2011 and 2015; and "ObamaRail" in the US.

2. The growth of public transport

Growth in transit has, in the past, been seen as a small part of the transport task, with car use growth expected to continue unabated. But now, "the exponential relationship between car use and public transport use ...indicates how significant the impact of transit can be," says the paper. "By increasing transit per capita, the use of cars per capita is predicted to go down exponentially." This so-called ‘transit leverage’ effect means that "even small increases in transit can begin to put a large dent in car use growth and eventually will cause it to peak and decline."

3. The reversal of urban sprawl

The increase in the density of cities can be seen as a multiplier on the use of transit and walking/cycling, as well as reducing the length of travel. For example, the return of small supermarkets to the central business districts of cities to meet increased local demand brings grocery shopping to within an easy walk for many. Overall, says the paper, "this reversal of urban sprawl will undermine the growth in car use."

4. The aging of cities

The average age of people in developing cities is rising. And the older people get, the less they tend to drive. Pretty simple. Although, as Newman and Kenworthy point out, with the younger cities of Brisbane and Perth shown to be peaking in 2004 along with Australia's aging cities, there are clearly other factors at work.

5. The growth of a culture of urbanism

One of the reasons there is less car use in aging cities is that older folk often move back into cities from the suburbs. Apparently, this was not foreseen during the Automobile City growth phase, nor was it foreseen that the children of the suburbs would drift to cities as they got older, rather than remaining car dependent. But these things have been happening for over a decade now, says the paper, and data presented by the Brookings Institute suggest it is a major contributor to the peak car use phenomenon.

6. The rise in fuel prices

"The vulnerability of outer suburbs to increasing fuel prices was noted in the first fuel crisis in 1973-4 ...when fuel price volatility was clearly reflected in real estate values," says the paper. And now, with oil commentators and oil companies admitting to the end of cheap oil, fuel prices "are obviously going to contribute to reducing car use growth."


So, what does it all mean? Newman and Kenworthy conclude their paper by saying that "the phenomenon of peak car use appears to have set in to the cities of the developed world," due to a combination of technological limits; growth in transit and re-urbanisation; aging populations and the emerging culture of urbanism; and rising fuel prices. The implications? For traffic engineers, planners, financiers and economists, say the authors, 'peak cars' means "a paradigm shift in their professional understanding of what makes a good city in the 21st century." And for the rest of us, it could mean the beginning of the end of one major source of climate change – our automobile dependence.