NSW commuters who switch transport modes during a journey will no longer be charged full fares.

End-of-week freebies for NSW commuters are to become a thing of the past, with the state government scrapping free rides for Opal card users who make more than eight journeys a week.

Instead, commuters will be given a 50 per cent fare discount after the first eight trips, as recommended by a recent government-commissioned Independent Pricing and Regulatory Tribunal (IPART) review.

"At the moment, we are forgoing more than $300 million of free travel across the network," Transport Minister Andrew Constance told reporters on Wednesday.

"Last year we actually lost money and at the same time we were increasing patronage."

As a sweetener, Mr Constance announced public transport fees will be frozen at least until the end of the 2016-17 financial year, with fare caps at $15 per day and $2.50 for seniors to remain.

And commuters who switch transport modes during a journey, for instance between a bus and a train, will no longer be charged the full fare for each leg.

They will be given a $2 discount from September 5 - a move Mr Constance says will provide an incentive for more people to use the public transport system.

"This is in response to a growing city where there's enormous pressures with congestion," he said.

"We can't continue to think in this state we can get from point A to point B with one mode of travel."

But the government's critics say scrapping free trips will not encourage more Sydneysiders to hop on a train, bus or ferry.

Opposition Leader Luke Foley said train commuters who travelled long distances five days per week, particularly those in western Sydney and the Blue Mountains, would be hardest hit by the changes, with some having to fork out hundreds of dollars more in transport costs a year.

"If you travel to work five days a week by public transport, you'll be paying 12.5 per cent more," Mr Foley told reporters.

"It's anything but a fare freeze."

The Greens said the $2 multi-mode discount "will mean some savings", but did not go far enough.

"We shouldn't be penalising people who make use of different modes of public transport," Greens transport spokesperson Mehreen Faruqi said in a statement.

Mr Constance said any savings from the new measures would be reinvested into the state government's public transport fleet.

Seniors groups have welcomed the fare freeze for older commuters.