Over a million people use Sydney trains on a typical day.
But this weekend, commuter chaos is expected with the city's rail network set to shut down for nearly three days.
Initially, industrial action was meant to start on Thursday but has now been delayed to the early hours of Friday morning.
It's expected trains will be operating again on Sunday.
Travelling across Sydney this weekend? Here's what you need to know.
Are any trains running this weekend?
Industrial action is due to start about 4am on Friday.
It's expected to continue until mid-morning on Sunday.
During this time, train staff will not be operating.
The ban was initially set to kick off on Thursday night, but after discussions between Sydney Trains and the Rail, Tram and Bus Union (RTBU), the union agreed to run a regular train service on Thursday to accommodate the Pearl Jam concert, which is expected to attract 40,000 people to Olympic Park at Homebush.
Planned maintenance will affect the Sydney Metro this weekend, adding extra strain to the transport system. Source: Getty / Lisa Maree Williams
Another 30,000 are expected at Olympic Park for the Saturday night show. Four A-League matches at Moore Park, including the derby between Sydney FC and Western Sydney Wanderers, will also be impacted.
There will still be some service reductions and cancellations on Thursday that will impact passengers travelling to and from Newcastle, the Central Coast, the Blue Mountains, the Southern Highlands, and the Illawarra.
The industrial action is expected to impact Sydney's inter-city and suburban lines.
Conversations between the NSW government and the RTBU are expected to continue on Wednesday afternoon.
What alternative transport is there?
If you're planning on travelling across Sydney this weekend, it might be a good idea to rethink your plans.
NSW Transport secretary Josh Murray said extra buses, ferries, and rideshare services will be rolled out.
But alternative services will be strained and under capacity.
"We will do everything we can, but we cannot accommodate one million people a day switching to other modes of transport," Murray said.
There is also track work on the Sydney Metro on Saturday and Sunday, with limited replacement buses running. Services from Tallawong to Chatswood will operate as normal, but services from Chatswood to Sydenham will not be running.
Why are unions striking?
The months-long dispute between the NSW government and the RTBU escalated on Tuesday when NSW Transport Minister Jo Haylen announced the rail shutdown.
It comes after union demands aren't being met.
The union wants a 32 per cent pay rise over four years and a 35-hour work week.
They're also calling for 24-hour train services across Sydney on weekends.
While the government agreed to that last weekend, transport officials said it was not possible this week and instead proposed running a 24-hour service between Hornsby and Strathfield.
"If we continue to try and run 24-hour services over the weekend that fact is that it will eventually lead to the failure of our rail network," Haylen said.
RTBU secretary Toby Warnes said while the initial four-day shutdown was the government's decision, the union was prepared to take some blame.
"Yes, the public may hold us responsible for the shutdown, but they should only hold us responsible for the shutdown on the Friday and the Saturday night, and only to the extent that they understand or that they believe that the government can't actually run 24-hour services," he told reporters on Tuesday.
"Our protected industrial action is always about causing a headache for the government, so they actually listen to the needs of their workforce. It’s never about disrupting the travelling public," he said.
"Our call for 24-hour transport has the benefit of being a pain for management and the government, while also resulting in improved services for commuters."
But Haylen said the networks weren't capable of running 24/7.
"We cannot jeopardise the maintenance of the rail system and we cannot jeopardise the services that people actually need to get to work in the morning and to get home to see their kids at night," she told the ABC.
She also said that factors like track maintenance meant overnight services wouldn't be possible.
"It is not a toy train set that you can tinker with and change overnight," she added.
Additional reporting by the Australian Associated Press
