The accompanying chart shows how public transport’s share of the journey to work varies with population density across 41 US and Australian cities.
It is taken from the same article that I mentioned in my last post. The authors, Dr John Stone and Dr Paul Mees, find there is only a modest relationship between population density and transit share (R2 = 0.229). They conclude that “higher density across the whole urban region is not the explanatory variable that many might expect”.
Los Angeles, for example, is the densest metropolitan area in the US – denser ever than New York – yet the chart shows public transport’s share of work travel in LA is much smaller than in NY.
If that seems counter-intuitive, your intuition could be right. The chart uses average population density calculated across the entire urbanised area of each city.
While that’s perfectly alright in some contexts, it doesn’t allow for the possibility that public transport’s ability to win travel away from cars is related to the morphology of density – the ‘peaks and troughs’ in the way the population is spatially distributed. It’s possible that the relative proportion of population in high density areas vs low density areas has a greater impact on mode share.
Using average density probably won’t present a serious problem with cities like Atlanta, Austin, Dallas, Phoenix and Portland where the population is overwhelmingly suburbanised at relatively uniform (low) densities. But it could have a big impact on places like New York which have an extensive ring of low density suburbs as well as a high density central region e.g. Manhattan and Brooklyn.
A way of dealing with this issue is to use weighted density rather than average density. This involves weighting the density of each suburb (or other convenient geographical unit e.g. traffic zone) by its share of the city’s total population. So a one km2 suburb with 5,000 residents (say) carries a lot more weight than another suburb of the same area that has only 1,000 residents. Read the rest of this entry »
Mr Mcleod has another interesting contention – he argues that Melbourne is unambiguously better and more liveable today than it was in 1960. Back then Melbourne had a population of around two million but now it has four million.
I have my doubts about the political wisdom of running that line but that’s neither here nor there – my primary interest is whether or not Mr Mcleod’s proposition makes sense.
I’ve no doubt the response of many people would be that housing in Melbourne is now less affordable than it was forty years ago and the roads and public transport are more congested. Some people also think it’s less safe, less equal and has a much larger per capita ecological footprint. For others, the footy lost something really important when the AFL was created.
On the other hand, many would argue that Melbourne is now more tolerant, more diverse and more exciting than it ever was. It’s now a city with a global profile, a better educated population and a vastly more sophisticated lifestyle. You can drive from the west to the south east fringe today entirely on freeway in under an hour in the off peak and you can take a train around the CBD. Read the rest of this entry »
Deirdre Macken makes the point in today’s AFR (gated) that a large proportion of Australia’s population is located in a very small number of primate cities, unlike the US where there are very many smaller cities.
She argues that if you want an urban lifestyle in Australia you either live in a large capital city or you camp out, whereas in the US you are spoilt for choice. Instead of making our capital cities larger, she asks, why don’t we build up our smaller cities?
Good question and if I weren’t about to go to the Zombie Shuffle I might well have something to say about it. Perhaps another day.
However for the moment let me just respond to her claim that “if Sydney were transported to the US, it would rank as the second-biggest city after New York. If Melbourne were transported to the US, it too would be the second biggest city, just pipping Los Angeles’s 3.8 million”.
A mere 3.8 million people in LA? I’ve got a lot of sympathy for journalists but this seems a bit too obvious. Perhaps Deirdre doesn’t do much travelling. She’s also got form when it comes to playing fast and loose with the numbers.
Sydney’s population is currently around 4.5 million and Melbourne’s is 4.0 million. Los Angeles had a population in 2009 of 12.9 million. In fact there are ten US cities that are larger than Sydney and fourteen larger than Melbourne (see here and here). Read the rest of this entry »
If the entire population of the USA were housed at the same density as Brooklyn, it would all fit in New Hampshire with space left over! See more on this infographic here. I calculate that the entire population of Australia could be accommodated at the same density as Brooklyn within a radius of about 25Km from the centre of Melbourne – the boundary in the south east, for example, would be around the intersection of the Monash Freeway and the East Link freeway. That would leave a lot of space left over! Read the rest of this entry »