Let’s take a top level look at Sydney for a moment. According to the Census, the city was home to 5,029,768 people as at 2016, which followed 12 years of hyper-growth, whereby Sydney’s population increased by 845,000 or 20%:

The primary cause of Sydney’s growth is mass immigration, which has run at turbo-charged levels, easily offsetting domestic outward migration:

Few living in Sydney would argue that the city is functioning effectively at its current size. Sydney’s roads are hideously congested, its trains and buses are sardine-packed, as are its schools and hospitals, and housing is among the most expensive in the world.
Bottom Line: liveability is being crushed, especially for residents in the city’s west where most of the population growth is flowing:

Yet despite these obvious truths, proponents of mass immigration continue to argue that growing Sydney to a city the size of London is desirable. Enter the latest spruiker named Philip Vivian, a director of architecture at design firm Bates Smart, who has penned the following drivel in The Australian:
Sydney’s population is predicted to increase to about nine million by 2061. As Australia’s economic powerhouse, Sydney needs a growth vision that will transform it into a sustainable and equitable global city. The low-emissions alternative to greenfield suburban sprawl — our current model — is to create a series of compact, connected high-density clusters that support walkable, mixed-use communities. This is a polycentric city model.
This model, which is evolving in other global cities such as London, will require a systemic shift in Sydney’s growth pattern, including minimising greenfield development, adopting a zero development green belt, and focusing on re-densification of our existing suburbs and infrastructure around public transport. There should be a citywide metro transport network and co-ordinated land-use and transport planning to create density clustering and connectivity.
This urban model will produce a more economically productive, socially inclusive and liveable city…
The strain in Sydney makes clear that our urban model is environmentally, socially and economically challenged. We need to start thinking now for a denser, low-carbon future that is resilient and sustainable into the next century.
Vivian’s claim that densifying Sydney “will produce a more economically productive, socially inclusive and liveable city” was destroyed by Infrastructure Australia’s latest report, which showed that no matter what Sydney does to cope with its migrant influx – i.e. builds up, spreads-out, or does a combination of the two – public transport’s modal share will barely increase, road congestion will dramatically worsen, and access to jobs, schools, hospitals and green space will all deteriorate as Sydney’s population balloons to 7.4 million people by 2046 (let alone to the 9 million people projected for Sydney by 2061):

The Urban Taskforce has also projected that Sydney will transform into a high-rise ‘battery chook’ city mid-century, whereby only the very wealthiest can afford to live in a detached house with a backyard:
Population boosters like Philip Vivian need to clearly articulate why growing Sydney’s population by another 4 million people in just 45 years (89,000 people a year), primarily via mass immigration, is in existing residents’ (and future residents’) best interests.
Because as it stands, Sydney is barely coping with a populations of around 5 million, and will inevitably grind to halt if Australia’s mass immigration ‘Big Australia’ program continues.
Thankfully, readers of Vivian’s article in The Australian have reacted furiously, overwhelmingly rejecting his Sardine can vision in the comments section.