Is Turnbull's '30-minute city' a serious election issue?

The transition from 150 years of spreading urban form to the much higher densities implied by the 30-minute city would be an extraordinary challenge for Australia’s cities, both financially and politically.

We can take it as given that none of the politicians have calculated either the financial or economic costs of this idea. They don’t know if the benefits exceed the costs and they haven’t thought about whether there might be better ways the massive government funding required might be spent.

But the problem isn’t just one of unrealistic and unattainable promises about the future. Another crucial point is many firms don’t want to locate in a village where they’re theoretically restricted to drawing workers from the local population. And what about customers and suppliers?

Many firms want to congregate in a limited number of very large activity centres, especially the CBD and a handful of major suburban activity centres. That’s because, although big centres come with downsides like higher rents, many firms and organisations get an increase in productivity from proximity to other firms i.e. agglomeration economies. Moreover, activity centres aren’t identical; they tend to specialise in one or two industries (see Are all suburban centres the same?).

Another problem is most workers don’t choose the fastest possible commute. They’re also interested in maximising housing quality subject to affordability. They tend to trade-off commute time for housing attributes like a bigger dwelling. In many cases, the optimum location for a household depends on the disparate job and education destinations of multiple household members e.g. mum, dad and children.

Marchetti’s constant suggests that commuters have a travel time budget; given an increase in travel speed, many will elect to commute further for a better dwelling. But note the figure of 30 minutes commonly associated with Marchetti’s constant is an average across all commuters; it does not indicate a maximum acceptable commute time for individuals as Messrs Turnbull and Albanese appear to assume (see Turnbull’s Smart Cities Plan: is that all there is?).

The 30-minute city pretty well already exists for traditionally highly local trips like food shopping and getting to primary school – 90% take less than 30 minutes. But the news isn’t good in terms of Mr Albanese’s ambition that primary students cycle, walk or take public transport; 70% of primary school trips are made by car (see Surely the 30-minute city makes sense for primary school trips?).

The objective of lowering travel times is a good one but we need to understand what the financial and social cost of each increment in improvement involves and whether or not it’s worth it. At present, Australian cities are a long way from the 30-minute ideal – even by car – when it comes to key travel purposes like getting to work, high school and tertiary education, as well as visits to family and friends.

Australians should be very suspicious of the bona fides of politicians who set very long-term quantitative targets. They’re attractive to voters because they sound tangible and therefore seem authentic. They’re irresistable to politicians because they’re so long term they don’t have to worry about the financial or economic costs, or whether the supposed benefits are even real i.e. they won’t be called to account.