Per capita passenger kms by car vs public transport in Australia's eight capital cities. Data source: BITRE

Tyler Cowen at Marginal Revolution linked to a piece in the Washington Post by Brad Plumer last week asking, Why aren’t young Americans driving anymore?

That’s a challenging question I’ve discussed before (e.g. Why is Gen Y driving less?). It’s complex because there’re differences between countries on some key measures, as well as between men and women.

Mr Plumer reckons it’s down to a combination of factors: the recession; the cost of driving has gone up; it’s harder to get a licence; more young people are living in transit-oriented areas; and technology is making it easier to go car-free.

Professor Cowen suggests it might also be because young Americans are working less and, more speculatively, “because it’s easier to have sex without driving to get it”.

 

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Young people aren’t the only ones who’re driving less. The first exhibit shows per capita travel by private vehicles (i.e. after taking account of population growth) has fallen since 2003-04 in Australia’s capital cities. The second shows total travel by private vehicle in those cities plateaued between 2003-04 and 2009-10 notwithstanding strong population growth.

It’s likely there are a number of reasons for the change. Higher petrol prices and the impact of the GFC are common explanations and are undoubtedly important, but they don’t provide a complete explanation.

Here’s a summary of the various hypotheses I’ve collected around the traps (see herehere and here) to explain the decline in travel:

  • Demand for travel is saturated – almost everything we want to get to is now within a reasonably short drive.
  • Higher levels of traffic congestion and slower average speeds – it’s too hard nowadays to travel long distances within our capital cities.
  • The population is getting older – retired people spend less time on day-to-day travel
  • Greater reliance on electronic communication – there is more scope to work and conduct personal business, shopping, banking and social networking without travelling.
  • Home offers more entertainment options than in the past e.g. computer and TV, reducing the need for travel
  • Driving costs more – although cars are cheaper to buy, insurance is expensive for young drivers, drink-driving penalties are severe, and obtaining a driver’s licence is both arduous and expensive
  • Young people stay longer in full-time education, carry debt on student loans and experience high rates of under-employment – they’re demand for travel is lower as is their ability to buy and operate a car.
  • More air travel – more time is spent on overseas holidays and business trips and hence not driving at home.
  • The age at which people have their first child is later, reducing the utility of car ownership
  • Shopping centres – increases in the density of larger, more diverse centres with longer-lasting perishables means fewer shopping trips are necessary
  • Migrants and overseas students studying in Australia generally come from countries where car use is much lower so they’re less inclined to use a car here
  • Better public transport services have attracted travellers away from cars – most Australian cities enjoy improving service frequencies, a longer span of operating hours, and in some cities extended networks.
  • Less emphasis on cars as coming-of-age symbols – changing mores mean there’s less need for a “shaggin’ wagon”
  • Smartphones have replaced cars as a means of providing social connection.
  • Cars are now commodities and are no longer as useful in signalling status as they once were
  • Slowing in the growth of female workforce participation – the dramatic growth of the last 40 years, which increased travel, has slowed. There’s a small fall in male participation.
  • More people live at higher densities in accessible locations like the inner city – cars aren’t essential and parking is in any event too expensive or too hard to find
  • The number of jobs has grown much faster in the city centre in recent years, where public transport is at its most competitive, than in the suburbs. Traffic congestion and high parking charges makes driving to the CBD less attractive.
  • Greater awareness of the negative environmental implications of car travel and the health benefits of active travel modes.

In their study of the travel behaviour of 20-29 year olds in Germany, France, Great Britain, Norway, Japan and the USA , Kuhnimhof et al concluded that the key factors underlying the reduction in driving are more young adults in tertiary education, lower workforce participation, and starting families at a later age.

Smartphones are often put forward as an important explanation but I’m not convinced. Neither are Kuhnimhof et al – they find they have negligible impact.

I’m not persuaded that the standard explanations from planners, particularly improved public transport and a growing preference for higher density living, are an especially important part of the explanation either (although I expect they figure in there somewhere).

The fact is our understanding of what underlies this change isn’t well developed (yet). There’s still insufficient information about what sort of travel is affected e.g.is it fewer trips? are trips getting shorter? is it mainly certain purposes?

We’ll have to wait for better research but if I had to guess at the key factors, I’d put my money on rising petrol prices, increasing traffic congestion and the sorts of structural social and economic changes identified by Kuhnimhof et al.

Total kms of travel in Australia's eight capital cities. Source: BITRE