Cheaper Vic train tickets 'not forever'

Cheaper Melbourne train tickets won't be around for long, public transport advocates predict.

Train ticket prices will be slashed for residents in Melbourne's outer suburbs, but experts expect the government to claw back the cash within years.

Public Transport Users Association president Tony Morton predicted that after the November state election, the government would try to get back some of the $100 million it is giving up.

"There is real pressure to jack up the base fare," Mr Morton told AAP.

He said similar price cuts in 2007 were overtaken by base fare rises within several years.

Trams will also be free in Melbourne's CBD from New Year's Day in a move to help tourists.

Mr Morton said tourists had complained about buying a myki pass for one or two trips - but said many of them used public transport to leave the CBD.

Premier Denis Napthine said the $100 million-a-year public transport changes would boost tourism and save money for Melbourne families.

"This will be a real boost to Melbourne's attractiveness, Melbourne's liveability and Melbourne's business credentials," Dr Napthine said on Wednesday.

Victoria Tourism Industry Council chief executive Dianne Smith welcomed the election-year announcement but said communication needed to be clear for visitors to know their ticketing obligations.

"This is a win for Melbourne's significant international student population and will further enhance the city's reputation as a world-class study destination," she said.

Opposition leader Daniel Andrews said Labor would keep the price cuts if elected.

But he said Labor was focused on reducing crowding on trains and trams, and relieving traffic by removing 50 level crossings.

Dr Napthine said the government would reveal in the May budget how it planned to pay for the $100 million-a-year price cut.