An emergency court hearing might be needed to ward off the largest shut-down in recent memory on Australia's busiest train network.
Trains from Newcastle to Wollongong and across Sydney are due to lay dormant from Friday morning until Sunday night amid an escalating pay dispute between the NSW government and drivers.
The Labor government had warned the public about a four-day stoppage but that was reduced to three days on Wednesday, which the Rail, Tram and Bus Union said was due to train officials misreading its initial demands.
After knocking back a proposal for 24-hour weekend trains, Transport Minister Jo Haylen said the onus was on the union to drop its work bans.
If that did not happen, all options were on the table including court arbitration, she said.
Fair Work Commission hearings were twice needed by the previous NSW coalition government to break deadlocks with the union.
The train network moves more than one million people on a typical day.
"The government will keep its options open, but right now, our focus is to bring this together, not to take court action and to drive it apart," Ms Haylen said.
"My number-one priority is minimising disruption to passengers and keeping the network moving."
That's proving a challenging task under the weight of other union work bans limiting kilometres driven and signal operations.
The industrial action resulted in more than 100 train cancellations during the Tuesday evening peak, stoppages along inter-city lines and re-working of shift duties.
Premier Chris Minns has weighed into the fray, calling leaders of the rail union and peak body Unions NSW, but the parties are in a stalemate.
The union wants four annual pay rises of eight per cent and a 35-hour work week, while the government has not budged since June from its offer of 11 per cent over three years.
Train union state secretary Toby Warnes denied a concession had occurred to allow operations on Thursday, saying its action "clearly specified it would only start on Friday".
He also described the shutdown as "a major overreaction" and suggested work bans would only cause some disruptions over the weekend.
Workers are being asked to work from home on Friday to ease the strain on buses replacing trains. (Bianca De Marchi/AAP PHOTOS)
"They haven't been engaging with us on the issues we need them to engage with us on," he told Sky News.
"And we're hoping that this big hoo-ha will bring about that engagement again."
The continuing stand-off has resulted in workers being asked to plan work-from-home arrangements on Friday to ease the strain on bus replacements.
"We will do everything we can, but we cannot accommodate a million people a day switching to other modes of transport," transport secretary Josh Murray said.
The pay stand-off comes after services were run around the clock over the previous weekend to ward off stop-work bans.
Transport officials said continuing services around the clock from Thursday to Sunday was not sustainable due to maintenance schedules.
The Sydney Metro from Chatswood in the north to Sydenham in the inner west is also closed for maintenance on the weekend, with Transport for NSW advising commuters to "use train services".