Sydneysiders have been warned that more than 1,000 train services are expected to be canceled by the end of Wednesday and those that do run could suffer delays of up to several hours as the state government vows to explore legal action to remove "Intolerable" strike action continues. Enter Thursday.

As of Wednesday afternoon, about 400 flights had been canceled and less than 20% were running on time or not at all. The T4 Eastern Suburbs and Illawarra lines, T1 North Shore, Western and T8 Airport and Southern lines are worst affected by the United Rail Union's work ban.

Chaos wreaked havoc throughout the morning, leading to long queues of people waiting to change buses and reports of journeys between the two suburban stations taking 40 minutes and trains often being stuck on platforms due to a lack of rail workers.

However, the transport authority said if certain work bans, particularly those related to maintenance, continue to be observed, disruption will worsen later in the day and worsen further on Thursday.

NSW Transport Minister Jo Haylen described unions as a "boa constrictor" "strangling" the train network and the consequences of the work bans as "unbearable".

Acting Premier Penny Sharpe said the work bans that came into force on Wednesday were having a "serious impact" on commuters and businesses across Sydney and "we are currently considering all legal options to ensure these conditions can be lifted" We can get trains running again on time."

Sydneysiders were told to start their journeys as soon as possible for the rest of the day, with transport authorities warning train delays were expected to be worse on Wednesday night and unreliable during the evening peak hour.

"Looking ahead into the afternoon and evening, conditions are going to get worse for trains and crews, and we're also seeing some severe weather coming up that could make afternoon travel more difficult," Department of Transportation Secretary Joshi said. Murray said.

"We are saying to vulnerable travellers, emergency workers or anyone with essential travel this afternoon, please leave now, make arrangements and do not rely on the afternoon peak service," Murray said.

Sydney Trains chief executive Matt Longland said the Electrical Union's (ETU) refusal to carry out maintenance on Tuesday night caused significant delays early on Wednesday. But actions by several United Rail Unions - negotiating a new pay deal with the government - have added to the confusion.

Langland said he had received advice from the ETU to keep maintenance bans in place on Wednesday night, suggesting commuter chaos would continue on Thursday.

Commuters turned to other modes of transport, with long queues forming outside some train hubs including Bondi Junction, while metro services unrelated to the ban on train network work were increased to meet the extra demand.

Among the bans imposed on Wednesday is an order for drivers to drive trains at slower speeds than necessary - a speed level that was gradually reduced as the pay dispute continues.

The impact of the work ban is being felt across the state, with the daily Bathurst Bullet Train service canceled and replaced by buses between Lithgow and Bathurst.

The new strike action comes as the United Rail Union considers the state government's proposal to raise wages.

Eight months into negotiations on a new pay deal, with proceedings before the Fair Work Commission and the Federal Court, Helen announced proposals for a 13 per cent pay rise, a 1 per cent efficiency boost and a 1 per cent super pay rise over four years - well below what she would have received over four years The railway union's merger demand reaches 32%.

Helen said the sweet offer, announced this week, was achieved through a deal that would merge the two national agencies that operate Sydney Trains and regional trains over the next four years. The merger is expected to drive productivity gains and financial savings, including possible job cuts, to fund an additional 1% of growth.

Helen urged rail unions to "put taxpayers' interests at heart" and consider what she called the government's "final proposals".

Railway unions have until Thursday to consider the proposal.

NSW Rail, Tram and Bus Union secretary Toby Warnes appeared lukewarm on the proposal. "We're a little bit disturbed by the fact that the government has only found 1% of savings out of it, and that 1% is just from unemployment," he said.

"So that's obviously something we're not too happy about. I don't think 13 per cent growth over four years is going to reduce that number."

The FWC cannot be called upon to resolve the substantive dispute - pay and conditions - until February.