Sydney train industrial action causes delays, threatens New Year's ...

Sydney commuters are gearing up to face a chaotic public transport network in the lead up to New Year's Eve as NSW Police warned the annual Sydney Harbour fireworks could be axed if disruption continues.

Train workers across the city are set to begin industrial action after a Federal Court ruling in favour of the Rail, Tram, and Bus Union (RTBU).

The union's demands have not changed, and the NSW government is showing no signs of budging.

Already 52 services have been affected, and passengers are being warned to expect more delays and cancellations across the Sydney Trains, Intercity and NSW Trainlink network. 

Passengers have been urged to delay non-essential travel if possible or consider alternative transport options.

South Coast Line passengers were impacted from Thursday evening with trains not running between Wollongong and Bomaderry in both directions.

A very limited number of replacement buses are being organised.

NSW Police Commissioner Karen Webb said she had "grave concerns" about the risk industrial action could pose to those "trapped in the city" after New Year's Eve celebrations at Sydney Harbour.

"I haven't ruled out that I will recommend to government that we cancel the fireworks," she said.

"It's that serious because 250,000 people ... come in during the day, they spend all day in the city but when it's time to go, when the fireworks are over, the job is to get them out safely and quickly and if there's no transport, we can't do that."

A spokesperson for Transport and Acting Night-time Economy and Tourism Minister Jo Haylen said the government was considering Commissioner Webb's comments.

"If that's the police commissioner's operational view, we're going to take that seriously," they said.

It is still unclear exactly how industrial action will impact Sydney's train network during it's busiest festive period, said the NSW government.

With large crowds expected across Sydney's public spaces for the New Year's Eve fireworks, the NSW government will be faced with a heavily congested public transport network. (City of Sydney: Daniel Tran)

An additional 1,000 train services have been scheduled for New Year's Eve in what is the busiest night of the year for Sydney Trains, according to Sydney Trains chief executive Matt Longland.

"We've been planning a number of agencies, including Sydney Trains, for the last nine months to prepare for New Year's Eve," he said.

Transport for NSW secretary Josh Murray said the industrial action could impact about 50 per cent of train services across Sydney ahead of New Year's Eve.

"That is not just impractical, it is not just a nuisance factor for government as was stated, it is reckless. It is impossible to run New Year's Eve at that kind of restriction," he said.

Ms Haylen said that trains carry over a million passengers every New Year's Eve across over 3,000 services every four to five minutes across Sydney's harbour.

"This is significant industrial action and that's why the government is taking every legal step available to us to protect passengers and businesses on New Year's Eve," she said.

"It's unfair on passengers that this is occurring at this time of year."

Throughout the past several months of negotiations between the RTBU and state government, the union has dug in their heels over what they want for their rail workers.

Ms Haylen said the government and union were "a long way apart" in their enterprise bargaining agreement negotiations.

Transport for NSW has issued a travel alert for 12 train lines across Sydney, warning of anticipatory delays because of ongoing industrial action. (ABC News: Keana Naughton)

The RTBU, which represents Sydney Trains workers, has called for a 32 per cent pay rise over four years, or an 8 per cent annual increase, and a 35-hour work week without a reduction in remuneration.

Union members want to see an additional 1 per cent employer superannuation contribution, and for super to be payable on all hours worked and while on parental leave.

It has requested training allowances as well as meal allowances for call outs.

The union wants employees to be paid a penalty if they are not paid correctly or on time.

The RTBU wants annual leave increased to five weeks for non-shift workers and six weeks for shift workers.

It wants overtime to be paid as double time and on the day.

For employees undergoing fertility treatment, the union wants one day of paid leave for each appointment associated with fertility treatment. 

The state government has since lodged an application with the Fair Work Commsission (FWC) to limit the impact of the anticipated industrial action. 

The next hearing will take place on Monday at 10am. 

Ms Haylen said the government made the application under Section 424 of the Fair Work Act on the grounds of community safety and economic harm.

Jo Haylen says the government and union were locked in negotiations. (ABC News: Ethan Rix)

The Fair Work Act gives the FWC the power to block industrial action if the action will endanger the life, personal safety, health or welfare of people, or cause significant damage to economy.

"We will not negotiate with a gun to our head and we want a service that is reliable for families and businesses this time of the year," Ms Haylen said.

"The government is pursuing all legal avenues to prioritise passengers, to protect them and businesses this time of the year."

By Thursday night, the government had not been informed how the union would implement the 200 bans it signalled would form part of industrial action.

Transport for NSW also issued a travel alert for 12 train lines across Sydney, warning of anticipatory delays because of ongoing industrial action.

Mr Longland said his department was unaware how many bans would be applied and when.

"Our focus … has been to resolve the outstanding issues of the enterprise bargaining agreement. That's what we want," Mr Longland said.