Over the next 30 years Australia’s population is to grow by 11.8 million people leading to a warning from the federal government’s peak infrastructure agency that major capital cities will decline in quality of life and economic productivity if governments fail to plan for the boom in population.

According to a new report released today by Infrastructure Australia, Australia’s population will grow by the size of Canberra each year for the next 30, turning Sydney and Melbourne into cities comparable to the like of Hong Kong, New York and London of today.

In the next 30 years, Sydney is projected to grow by 2.6 million people, Melbourne by 2.7 million while Brisbane will grow by 1.6 million people and Perth by 2.2 million.

The report follows on from growing debate about immigration levels sparked by comments made this week by former prime minister Tony Abbott who called for the migration rate to be halved, partly because of a lack of infrastructure to sustain growing populations.

Infrastructure Australia warns growth of the size predicted will “transform” Australia’s cities and if the government fails to “effectively anticipate and response to growth, the likely results will be declining economic productivity, increasing environmental pressures and a marked reduction in each city’s quality of life”.

Huge change facing Aussie cities

Urban planning specialist James Rosenwax, Executive Director, Brilliant Cities, told nine.com.au the report is a “great initiative” to “start the conversation”.

“It is a really important contribution to greater awareness for our community and our populations in general about in the increasingly rapid growth our cities will go through in the next 30 years,” he said.

“We’re going to be faced with huge change as we grow by up to 50 percent in our capital cities. If your think about this, it took us 230-odd years to get to our current population and that’s going to basically get close to doubled – we’ve got a huge challenge in our cities and we need to get ready for huge change.

“If we don’t change well in the next 30 years, it’s not going to be great for us. But if we do change well, lifestyle, liveability, productivity, everything about Australia will be better than it currently is.”

Rosenwax said the expected population boom means “we’re going to have to be challenged to look at different models of density to accommodate the populations necessary”.

“We can’t afford to continue to grow out because people need to understand if we continue to grow out and urbanise in the greenfield areas we have to provide all the infrastructure necessary to house those people and that’s water infrastructure, social infrastructure like schools and hospitals, energy and public transit as well. Doing that to a low-density population just isn’t feasible anymore.

“For Sydney, and Melbourne particularly, we need to be thinking about more diverse housing types and providing more diversity in our housing types in our cities,” Rosenwax said.

“We can still have cores of low-density, because that might suit some of our diverse population in the future, we can have cores of medium-density to accommodate increased population and we can have cores of high-density.

“That’s what a poly-centric city is all about – it’s providing not just one scenario, it’s providing a balanced mix of multiple scenarios across our entire cities to provide choice.”

Pressure placed on Melbourne and Sydney

In a series of “scenario planning” models, the report warns of increased congestion on Melbourne roads, suggesting that while “road construction remains important, the scale of capacity enhancements required to meet demand and in turn to moderate congestion, particularly during the peak, is not achievable through construction alone”.

The next 30 years will see increased pressure placed on Melbourne’s infrastructure and supporting services, particularly healthcare, as “the number of people in the state aged over 85 or over will grow by 220 percent”.

“Over the same period, the state’s school age population is projected to increase by around 450,000 students,” the report says.

“Funding and policy change focused on meeting demand, including increasing capacity, will be required to effectively meet increased demand.”

According to the report, in 2016, metropolitan-level access to hospitals was relatively high “with 87 percent of Melbourne’s population being able to reach a facility within a 20-minute drive or 30-minute public transport trip”. But by 2046 this will have declined.

Melbourne will also “experience a large increase in demand for school facilities”, the report says.

By 2046, Sydney’s population will total 7.3 million people – that’s an increase of 2.6 million from 2016, with jobs growing by 1.3 million to totalling 3.7 million.

The boom in population will see car usage grow, with daily kilometres driven will increase between 38 and 42 percent in the next 30 years, placing further strain on existing roads and contributing to congestion.

“Strategic road investments will still be necessary to ease localised congestion, but the projected increase in vehicle kilometres travelled indicate that road construction will not be sufficient. This reflects the need for a nuanced transport policy, where public transport and road investment, as well as demand management (including road user charging), each play a role in the city’s future network,” the report says.

The Harbour City will also “experience an unprecedented increase in demand” for essential social services and infrastructure with the public education system set to come under strain with a projected 173,000 additional students across the state, with 80 percent of that growth to occur in Sydney.

Quick-access to hospitals will also decline. In 2016, 80 percent of Sydney’s population was able to reach a hospital within a 20-minute drive or 30-minute public transport trip – by 2016 this will have declined to around 71 to 76 percent.

Sydney and Melbourne should aspire to 'healthy, productive and liveable' cities

While the IA report predicts Sydney and Melbourne will transform over the next 30 years into cities similar to what Hong Kong, London and New York are today, Rosenwax wants Australia to aspire to cities like Barcelona and Copenhagen.

“They have really taken not just the transport layer of city making seriously – they’ve taken huge steps in what we call in the city game modal shift, they’ve deprioritised the car and prioritised other forms of transport, active transport like walking and cycling,” he said.

“This is what makes truly healthy, productive and liveable cities, this is what we should be aspiring too. Cities that don’t have some of the social problems of super mega-high density – you’ve got non-communicable diseases that come about through inactive populations that live in high-density scenarios.”

In terms of which city out of Melbourne and Sydney are better placed to make the changes needed to become a city like Barcelona, Rosenwax said both “are racing against each other right now”.

“It is all about public transport and non-motorised access and both cities are making huge changes to the way we move and access facilities,” he said.

“Sydney, I think, is in a better position because we have the Blue Mountains to forcibly stop our growth and over time that’s going to force us to stop sprawling and it’s going to force a denser, more diverse and liveable community.

“The current situation in Melbourne – they’ve got trains, they’ve already got their tram networks established, they’ve got their cycling culture and networks established, they’ve got their sporting areas of excellence such as Melbourne Park, the MCG – they’ve got more diversity in terms of a city than Sydney currently has which is more one-dimensional than Melbourne right now.”

While Rosenwax welcomes the report from IA, he said more than just transportation modelling needs to be considered.

“City building is complex and we need to consider the energy layers, energy supply, water supply, social infrastructure supply and at the same time we model transport and it’s not until we can do this that we can really begin to understand what makes a city great and that’s the only way we are going to become a city as successful as a city like Barcelona or Copenhagen.”