Published by Australian Financial Review, Wednesday 10 October
The so-called Minister for Congestion Busting, Alan Tudge, is not only planning to direct migrants to regional areas; he’s also going to respond to population growth with loads of new infrastructure. The Minister seems to believe that with Australia adding the population equivalent of a new Canberra each year, we need an extra Canberra in terms of infrastructure each year.
The idea that 1.5 per cent more population should be accompanied by 1.5 per cent more infrastructure may be intuitive, but it’s wrong: we need less than that. And whatever new infrastructure governments do build should be rigorously chosen to provide for the most pressing needs.
There’s no doubt Australia has had enormous population growth in recent years. Sydney and Melbourne’s populations grew in the five years to 2016 at rates among the highest in the developed world, by 1.9 and 2.3 per cent each year. Brisbane, the Gold Coast, the Sunshine Coast, Canberra and Darwin also grew strongly.
And it’s also true that much of the new swathe of infrastructure projects that the Minister points to and that are under construction in Sydney, Melbourne and Brisbane are yet to come into operation.
For instance, Sydney’s WestConnex Stage 3 is not due to be opened until 2023, and the Melbourne Metro is not scheduled to carry passengers until 2025. The stock of roads has increased by much less than population growth: Brisbane’s road length grew by 1.1 per cent over the five years to 2015, while the population grew by 9.9 per cent.
Notwithstanding high population growth and only modest new infrastructure, it turns out that commutes have been remarkably stable. The average commute distance barely increased in the five years to the most recent Census in 2016, and there has been little or no change in the duration of commutes. Despite regular media coverage claiming the opposite, the impact of rapid population growth on commutes has been remarkably benign.
There is no simple formula for how many lane kilometres of road or track kilometres of rail, or how many trains or buses are needed per person. But recent Australian experience indicates the scale of new infrastructure a growing city can make do with while keeping commute distances and times stable.
A city with double the population of another does not have double the commute times or distances. Average commute times and distances in Melbourne and Brisbane are similar, even though Melbourne has twice the population of Brisbane. People in Canberra spend longer and travel further to work than those in Adelaide, even though Canberra has only a third of Adelaide’s population.
Cities cope while awaiting projects
These outcomes are not as surprising as they may appear at first blush. High-school geometry shows that if a city doubles in population while maintaining the same distribution of homes and workplaces across the urban area, the average beeline distance of a typical trip would only be 40 per cent longer, not 100 per cent.
In a simplified example, if a circular city with a radius of one kilometre doubled in area, the radius of the circle would rise from one kilometre to 1.4 kilometres, with 1.4 being the square root of 2.
Take Melbourne as an example. Its population grew by 2.3 per cent on average each year between 2011 and 2016 – that’s a factor of 1.023 each year. You would expect its average commute to grow by the square root of 1.023 per year: 1.14 per cent. But Melbourne’s average commute grew even more slowly, by only 0.20 per cent each year.
Instead of simply resigning themselves to longer commutes, many Melburnians changed where they lived or where they worked or how they got between the two, and the city’s density increased over this time.
Of course, even though population growth has had a remarkably benign impact on commutes, this is not to say that everyone is better off. Some people elect not to take a new job that’s too far from home; some pay higher rent or cannot afford a place they once could have.
But it is to emphasise that people are not hapless victims of population growth, depending for their wellbeing on governments building the next freeway or rail extension. Cities have coped, even though major new infrastructure projects are yet to be delivered. It turns out that building new infrastructure is far from the only way to cope with population growth.
Governments should therefore take a much more disciplined approach to building new infrastructure. They should not announce any new project before rigorously establishing their net benefits to the community. Instead of reaching for mega-projects, they should devote more resources to discovery of small projects with high net benefits that may be dispersed across the city.
With Victorian, NSW and federal elections in the months ahead, be very sceptical of “congestion-busting” election pledges.