The promises of Labor and the Greens fall even further short, the analysis by progressive think tank the Australia Institute has found, indicating Melbourne is on a long-term course towards overwhelming congestion on its roads and rail lines.

In one of its biggest commitments of the election campaign, the Coalition promised this month to purchase 95 new trains and 75 new trams, putting them in service between 2019 and 2026.

Minister for Public Transport Terry Mulder said "the new trains and trams would allow an extra 150,000 passengers to be carried each week day".

But the capacity boost will go less than half-way to meeting expected demand, according to the institute's analysis, which compared the figure with Melbourne's forecast population growth and public transport patronage growth.

Melbourne's population is forecast to grow between 19 and 23 per cent in the next decade, the Australian Bureau of Statistics says, from 4.4 million now to between 5.25 million and 5.45 million people.

Growth in demand for trains, trams and buses is forecast to be much stronger, increasing 42 to 48 per cent on today's levels, according to a 2012 report by Public Transport Victoria.

"It's unclear how these new trams and trains will be enough to keep up with fast growing demand for rail travel in Melbourne," Australia Institute researcher Tom Swann said.

Mr Swann acknowledged the government already had other trains and trams in the pipeline – eight X'Trapolis trains for the Frankston line, 25 high-capacity trains for the Cranbourne-Pakenham project and 41 E-Class trams – but said these still would not come close to meeting demand.

There are currently more than 1.1 million journeys a day on Melbourne trains and trams. Creating capacity for 150,000 new journeys a day would grow capacity by 13 per cent – lower than population growth and less than a third of expected demand, the institute found.

"If services do not increase as fast as the population grows, this is effectively a cut to services," Mr Swann said. "If services grow slower than demand, people will miss out."

The train and tram election promises of Labor and the Greens are more modest than the Coalition's: Labor has promised to buy 30 new Metro trains and 20 V/Line carriages and the Greens have called for an extra 50 E-Class trams.

Mr Swann said it was evident no party had based its promise around meeting passenger demand induced by population growth.

The city of Wyndham in Melbourne's outer west is forecast to gain more than 90,000 new residents in the next 10 years and currently has just five trains an hour on the Werribee line. The council has called for 13 trains an hour to meet booming demand. One-quarter of Wyndham's workforce works in the inner city.

"Wyndham City remains very concerned that the unrelenting nature and huge size of residential growth is still not recognised by government in terms of continuing funding for public transport upgrades," Wyndham transport portfolio chair Glenn Goodfellow said.