The City of Melbourne in April released a discussion paper canvassing the introduction of a Metro 2 and 3, among a raft of other major projects, as part of a 10-year future transport plan.
CBD rail patronage is expected to reach 200% of current capacity by 2031, with the Metro 1 and 2 critical to meet forecast demand, according to the discussion paper.
"But, even with the proposals floated by government, Melbourne's network would not be accommodating for growth given the rapid rise in population," professor Graham Currie from Monash University told Government News.
Latest figures from the Australian Bureau of Statistics show Melbourne experienced its highest-ever net annual population increase in 2016-17, adding 125,000 new residents to bring its population to 4.9 million.
Melbourne had the largest population growth of all capital cities, followed by Sydney (101,600) and Brisbane (48,000).
Professor Currie pointed to research showing public transport service provision per capita has been declining rapidly in Melbourne since 2011-12 as the city fails to keep pace with population growth.
Currie presented similar research to the Victorian Parliament in 2016 illustrating that while the state seems to be improving in service delivery since 2011, the state is "going backwards" per head due to the escalation in population growth.
Currie's findings show that car sales and ownership continue to rise, as do the costs and prevalence of urban traffic congestion, while two-thirds of Melbourne is serviced by bus only, and tram services come under increasing strain.
He argues that the Victorian government needs to invest more in public transport to meet the exponential forecast in demand for public transport.
"We need to grow; our systems are not big enough. Service is growing but the population is growing more, so per head we're now in decline," Currie adds.
While state governments across Australia have committed to massive public transport infrastructure projects, professor Currie said the current scope of some of these projects is not sufficient to meet forecast demand.
Currie argues that building more roads is counterintuitive.
"We need metros, high-quality light rail, good bus systems. We're still building roads in a lot of cities," Currie said.
"For successful mega city central areas we can't use a car, it's not possible."