About an hour after union representatives confirmed planned strikes for next week would likely go ahead, Premier Dominic Perrottet on Friday announced travel on Sydney Trains services would be free from Monday to Friday.

Rail, Tram and Bus Union (RTBU) Secretary Alex Claassens said one of the only ways to prevent rail services from being slashed to 30 per cent on Monday and Friday was for the government to make fares free for commuters on those days.

"We've been going on for way too long," Mr Perrottet said.

"Providing free travel for the week will ensure that industrial action does not occur."

Mr Perrottet described discussions with Mr Claassens and other RTBU representatives on Thursday as constructive.

He said he hoped the dispute would be resolved by the end of next week.

The union is pushing for changes to a new fleet of inner-city trains over safety concerns and wants a guarantee the government will pay for them.

The sides are due to sit down with mediators from the Fair Work Commission next Tuesday.

"They've made it quite clear that they've had enough," Mr Claassens told reporters on Friday.

"They would like to see this matter resolved once and for all - and on that point, we're all on a unity ticket."

He said the problem was every time an agreement was made at the negotiating table, someone else interfered.

"We can't keep going on this merry-go-round where we sit in a room, there's an agreement reached and then some other nameless bureaucrat or lawyer gets involved and changes the goalposts," Mr Claassens said.

The union previously revealed plans to open Opal gates for all customers but said it was forced to abandon the plan due to actions launched by the government in the Federal Court.

Australian Associated Press