Revellers could drive, get a taxi or catch public transport, including the train, after work bans and strikes resume from December 28, Rail, Tram and Bus Union secretary Toby Warnes told reporters on Tuesday.
"The fireworks are still going to happen, people are still going to make their way into the city," he said.
Members had to vote to resume existing plans that are "intolerable" to the NSW government, which took the union to court to stop them.
The union's re-notified actions could make it difficult to run additional services catering to New Year's Eve demand.
"It will mean they can't run quite as many trains, but there will certainly be trains running," Mr Warnes said.
Transport Minister Jo Haylen says industrial action was "intolerable" during Sydney's famed fireworks - the train network's busiest day - with more than one million people expected on the harbour foreshore.
"Any level of industrial action during this time is not acceptable," she said.
Industrial action could resume earlier if an injunction is lifted, as the union accuses the government of spending taxpayer money on legal challenges instead of negotiating wage rises.
Treasurer Daniel Mookhey urged the union to accept the offer on the table, which he would not disclose publicly.
"We've made a reasonable offer and showed multiple ways that can be realised," Mr Mookhey said.
"(It's) not a time to play chicken with the NSW economy," he said.
Commuters could be left stranded on New Year's Eve - the busiest day on Sydney's rail network. (Steven Saphore/AAP PHOTOS)
The union wants wages to rise eight per cent a year for four years, or at the rate of inflation if higher, while the state has proposed a total 11 per cent raise over three years.
Government and worker representatives were also before the Fair Work Commission on Tuesday, a day after Labor dragged the union to Federal Court to halt plans for pre-Christmas industrial action.
Business groups say the threat of further industrial action could change travel plans and reduce spending, spelling doom for struggling firms.
"If this strike goes ahead, some businesses will experience bankruptcy," Business NSW chief executive Dan Hunter said.
Opposition Leader Mark Speakman said the planned disruption was extraordinarily selfish.
"This Christmas, they've managed to gift-wrap chaos for the people of NSW," he said.