Australia's major cities have been hit by stifling congestion in recent years as their populations have swelled, but big-spending projects to alleviate traffic have largely proven ineffective.
This has prompted growing calls for the introduction of congestion charges to try to encourage drivers to stay away from the city centre or main roads, particularly during peak hours.
According to a report released this week by the Grattan Institute think-tank, a "modest" congestion charge in Australian city centres could reduce the number of cars entering by 40 per cent during morning peak hours and increase average driving speeds by up to 16 per cent.
The report said a scheme similar to those adopted in London, Singapore or Stockholm would address congestion without requiring additional large-scale transport infrastructure spending.
It suggested a three-stage reform, which would begin with a charge for entering the city during peak hours.
Within five years, charges would also apply to driving on busy main roads, and eventually a per-kilometre charge would apply to all roads.
"Excessive congestion is costly and wasteful," the report said.
"Decades of more roads and more public transport have given us the levels of congestion we see today. It's time for a new approach."
In recent years, Australian state and federal governments have spent hundreds of billions of dollars on new roads, highways, tunnels and public transport, but they tend to quickly fill up and have done little to address long commute times.
Transport infrastructure spending is currently at record levels of more than A$30 billion (S$28 billion) a year nationwide, about 50 per cent more than average funding, adjusted for inflation since 2005.
The spending boom has occurred as the populations of Australia's major cities have soared, mainly due to a steady influx of migrants.
In the decade to 2017, greater Sydney's population increased by 19 per cent from 4.3 million to 5.1 million, and that in greater Melbourne grew by 26 per cent from 3.8 million to 4.8 million.
In many cases, the major infrastructure projects in these cities have simply kept up with population growth and have not led to significant changes in commuting times or distances. Commuting times in recent years have remained relatively constant in Sydney and have dropped slightly in Melbourne.
Singapore was the first major city to introduce road pricing to reduce congestion more than 40 years ago, and others have followed.
New York is designing a scheme for Manhattan, and others have been proposed in Hong Kong, Beijing and Vancouver. Jakarta plans to introduce a scheme next year.
Yet, states in Australia have been reluctant to introduce schemes to charge drivers for road use, even though city councils and the federal Productivity Commission have supported them. State governments have often feared that the charges will be unpopular and insisted that existing efforts to expand transport networks are sufficient.
New South Wales Transport and Roads Minister Andrew Constance flatly rejected applying a congestion charge in Sydney.
"We don't need to put a tax on people in order to get them to change their behaviour," he told reporters on Monday.
"We need taxes to be deployed into brand new public transport."
Australia's transport infrastructure spending a year nationwide.
Victoria Premier Daniel Andrews also insisted that congestion charging was unnecessary.
"We are not putting tolls on existing roads," he told ABC Radio on Monday. "We have decided to invest instead in the biggest programme of upgrades in our public transport and roads network that the state has ever seen."
Some experts said cities such as Sydney and Melbourne should charge drivers for each kilometre travelled during peak hours rather than charging for entering the city centre, noting that congestion tends to be citywide and is not necessarily heavier in central business districts (CBDs). In addition, charges for the city centre can encourage drivers to take "rat runs", or alternative routes, to avoid the fee.
An editorial in Melbourne's The Age newspaper this week said that the city was not yet ready for a congestion charge, though it should be considered again in the future.
"With more than 900,000 using the CBD every day - a figure expected to increase to 1.4 million by 2036 - there needs to be some way to travel to the city," the editorial said.
"Deterring car drivers will not work without viable alternatives, and while big public transport infrastructure projects are under way and on the drawing board, it's still some years before these will be real things that people can use."