Sydney Train workers have voted to go ahead with a 24-hour strike on Monday, in a move expected to have chaotic consequences for commuters in Australia's largest city.

Key points: Sydney's train timetable will be significantly reduced from tomorrow

Sydney's train timetable will be significantly reduced from tomorrow The main disruptions will be on Monday, when workers go on a 24-hour strike

The main disruptions will be on Monday, when workers go on a 24-hour strike However, there are questions about the legitimacy of the union's text-message voting system

Less than 6 per cent of the Rail, Tram and Bus Union's (RTBU) 6,000 members in New South Wales voted in favour of calling off industrial action in a text message poll.

Industrial action will begin from today, when workers enact an overtime ban, meaning timetables will be significantly reduced.

The NSW Government has launched fresh legal action to try to stop the strike, with a Fair Work hearing scheduled for this morning.

The union had been locked in negotiations with Sydney Trains and the NSW Government for about a fortnight.

Screens at Central warn of significant delays from Thursday. ( ABC News: Taryn Southcombe )

They rejected a pay offer last week, but negotiations yesterday produced a new offer, which members subsequently voted on.

Yesterday, NSW Transport Minister Andrew Constance said he was still hopeful Monday night's strike could be averted, and that he would meet union leadership again that night.

SMS not legitimate: Minister

The integrity of the union's SMS vote has been questioned, with some union members complaining they did not receive a message.

Alex Claassens, NSW secretary of the RTBU, conceded the system was not ideal, but said it was the best method he had to conduct the vote.

Members who replied "Yes" wanted to cancel the action, while those who did not respond were counted as supporting the strike. "No" was not an option.

The RTBU vote was conducted via text message. ( Supplied )

"I don't think texting people like this is a legitimate way to canvas the views of the workforce," Mr Constance said.

Discussions are being played out amid several meltdowns on Sydney's railways since a new timetable was unveiled in November.

Mr Claassens said members were frustrated.

"We have been saying all along that we needed the Minister to come to the table and put some real positions down so our members are totally frustrated with everything that's been going on," he said.

"I think we all know that the straw that broke the camel's back was the introduction of the [new] timetable."

Mr Claassens said businesses should be allowing their employees to have Monday off work because of the disruptions.

"We have now got to a situation where by virtue of the fact that a few railway workers are having the day off, they're all predicting Armageddon tomorrow," Mr Claassens said.

Sorry, this video has expired NSW Transport Minister hopeful train strike can be averted

Mr Constance said he was still hopeful Monday night's strike could be averted.

"It [the strike] is not in the interest of 1.3 million people on our railways come Monday," he said.

"Call off this strike, allow the workforce to be consulted and we'll go from there."

NSW Opposition leader Luke Foley said the State Government had declared war on its own workforce.

"The Berejiklian Government has lost control of the railways, and 1 million rail commuters suffer as a result," he said.

"I urge the union and Government representatives to resume negotiations."

Months of railway chaos

The new timetable, which included 1,500 extra bus, train and ferry services in Sydney each week, has put pressure on the railways.

On December 10, evening peak hour turned into chaos after a fatality on the tracks, with travellers at the busy CBD stations of Town Hall and Wynyard advised to walk to Central, Museum, St James or Martin Place.

The dysfunction climaxed on January 9 when the Harbour City's train network was plagued by widespread delays and cancellations, overcrowded stations and carriages.

Commuters complained about journeys being hours longer than usual and platforms being closed at some stations, while Mr Foley described the conditions as "third world".

The strike is expected to have chaotic consequences for Sydney's train network. ( ABC News: Nour Haydar )

An unexpected spike in sick leave, coupled with the new timetable and stormy conditions have been blamed for the situation, which were described by NSW Transport Minister Andrew Constance as "an act of God".

Earlier this week, 16 people were taken to hospital after a train slammed into a barrier at Richmond Station in Sydney's north west, when it failed to slow down.

That incident has sparked three separate investigations.