Instead of a world-famous bang, Sydney could ring in the New Year with a whimper if a threat to axe the harbour city's fireworks over transport safety fears is realised.
Last-ditch talks and negotiations are underway after the NSW police commissioner said planned industrial action on the rail network meant she had grave concerns about public safety for the city's biggest annual event.
As one of the first major global celebrations to ring in the new year, Sydney's spectacular midnight fireworks display is a key tourism event and is well-watched around the world.
Organisers say it is watched by one million lining the harbour foreshore and another 400 million people globally.
Police Commissioner Karen Webb hasn't ruled out calling a halt to Sydney's New Year's Eve fireworks. (Dean Lewins/AAP PHOTOS)
But this year's event is approaching under a cloud of union-led train disruptions, leaving Karen Webb worried about how tired, tipsy revellers will depart the city after midnight.
"I have grave concerns," the commissioner told reporters on Friday.
"I haven't ruled out that I will recommend to the government that we cancel the fireworks."
Sydney's Lord Mayor Clover Moore said she would request an urgent meeting with the NSW premier if police formally recommend cancelling the event, which is organised each year by the council she leads.
"We will do everything we can to ensure the fireworks can go ahead safely," she said, highlighting the event's estimated $280 million in economic benefits to the city.
The Labor government plans to ask the Fair Work Commission to cancel the industrial action over safety concerns following earlier action in the Federal Court that temporarily halted union work bans.
However, Rail Tram and Bus Union officials on Friday accused the state government of resorting to "hysteria and scaring the public" and getting Ms Webb "to tell fibs".
Trains would run, albeit with drivers obeying work bans effectively halving how far they would drive, state secretary Toby Warnes said.
It was ultimately up to Sydney Trains to decide how many trains ran, he said.
"The information that the police commissioner has, in terms of disruptions, is not likely to be correct," Mr Warnes said.
Work bans were blamed for scores of train delays and cancellations across the state on Friday - many workers' final day in the office for 2024 - while the South Coast line was shut completely.
But the real cause of that disruption was trackwork, union president Craig Turner said.
New Year's Eve is the busiest day on Australia's largest rail network as millions of people are shuttled around Sydney Harbour and elsewhere in the city for fireworks and other celebrations.
Some 3200 services run about every five minutes throughout the day, with crunch time coming in the hour after midnight as the masses try to leave together.
New Year's Eve is the busiest day on Sydney's rail network. (Dan Himbrechts/AAP PHOTOS)
NSW Transport Minister Jo Haylen poured scorn on the union's portrayal that work bans were a means of getting the government back to the negotiating table.
"They say, 'well, let's talk about it'," she said.
"But the fact is unless you agree with them, there's no endpoint."
Unions continue to demand four annual wage increases of eight per cent, which Premier Chris Minns has said is unaffordable and could not occur while he is denying nurses a similar claim.
The government previously offered 11 per cent across three years, including superannuation increases.
Mr Warnes wants commuters frustrated by the industrial action to bottle their anger until the 2027 state election.