The Rail, Tram and Bus Union failed to reach a breakthrough in emergency talks with the NSW government on Wednesday night after beginning rolling industrial action that morning.
Travel to weekend NRL and AFL finals - including the Swan's sold-out game against Port Adelaide at the SCG - and the Bledisloe Cup rugby union fixture could be disrupted because of a union ban on the provision of the extra services required.
The rail union has taken issue with plans to convert the T3 line to driverless metro standards. (HANDOUT/AAP)
The union is also threatening to shut down the entire T3 train line - from Liverpool in Sydney's southwest to the city centre - if the government pushes ahead with plans to convert part of it to driverless metro standards.
The conversion requires closing the Sydenham-Bankstown section from September 30, but Transport Minister Jo Haylen warned union work bans could delay the construction altogether at a cost to taxpayers of $100 million per month.
The government has also been left scrambling to find enough replacement buses to service routes on the busier-than-usual weekend.
"We will add as many services as we can in the amount of time that we have," transport secretary Josh Murray said on Thursday.
The rail union says the conversion is unsafe and represents a different beast to newly constructed metro lines elsewhere in Sydney.
Jo Haylen is trying to find buses to service rail routes with three big footy matches scheduled. (Jeremy Piper/AAP PHOTOS)
NSW secretary Toby Warnes said the Bankstown train line was 150 years old and operated at ground level, putting people at risk of being struck by the driverless trains.
"We've said in the past we're not going to stand in the way of (the conversion), but it has to be safe," he told ABC radio.
"We can't allow flawed plans running along a ground corridor putting people and passengers at risk."
Mr Warnes rejected claims one of the union's demands was for a qualified driver to be placed on each of the automated metro services.
Worker representatives are also growing frustrated with the government as it tries to negotiate a new enterprise agreement for train staff.
The union is asking for a 32 per cent pay rise over four years, a 35-hour working week and a series of safety improvements.
"Two things are going on here in parallel," Ms Haylen said of the twin disputes.
"For some months (we) have been in the bargaining room going through the log of claims ... what is separate to that is the union's opposition to the metro conversion."
An agreement could still be met before the weekend, she said.
"My door is always open because we want to make sure families can get to the footy this weekend," she said.
The industrial action is the most significant from the union since the Labor government came to power in March 2023.
Sydney's transport network was gripped by chaos in 2022 as unions and the then-coalition government negotiated over pay and provisions on new, overseas-built trains.
