'Completely full': Commuters feel the pinch of industrial action

Sydney Trains has reduced Thursday's services to a weekend timetable, meaning trains will run every 15 minutes during peak hour instead of every eight.

The indefinite ban on overtime comes ahead of Monday's full-day rail network shutdown, after thousands of rail workers voted to reject a government pay deal and take industrial action.

On Wednesday, Sydney Trains urged employers to talk to staff about alternative arrangements including working from home, taking annual leave or altering their start and finish times.

However, passengers stuck catching trains on Thursday were feeling the effects early, with services from Parramatta and Penrith packed.

Commuters complained on social media about being "packed like sardines" particularly at Parramatta station, while others wondered how a ban on overtime could create a need for such a large reduction in services.

But not all services seemed to be affected by the industrial action. One commuter said their service between Hurstville and the City was normal, while another said their 7.30am train from Gosford to Central was less crowded than usual.

Some commuters told Fairfax Media they supported the train workers' industrial action.

"I'm actually behind the train drivers because what they have been offered, I think, is a very low amount compared to what some of the higher paid people have been given recently," said Jill, 64, who catches the train four days a week to Parramatta for work.

Rail, Tram and Bus Union state secretary Alex Claassens told the media the overtime ban was about "people being able to have their days off".

"Anybody that runs a business knows you can't continually run it on overtime, and if we're running a railway that requires people to work overtime, we've got a real problem," he said.

Mr Claassens said negotiations with the government would continue at 11am, and the union hoped for some resolution today before Monday's planned network shutdown.

John and Maria, who were taking the train for an appointment, said the transport situation on Thursday was confusing.

"It's not so much the strike, it's just knowing whether we can get to our destination or not," John said.

"We're trying to go to Bondi and we don't know whether there will be a train to Bondi ... the next two days are very confusing."

However they said they supported the train drivers' request for better pay.

"I personally feel bad, knowing that, three days ago, they were saying on the news, the Premier of NSW was saying they have more money in surplus than any other government ... yet they're reluctant to give some money to the drivers," John said.

Beth, who catches the train to Parramatta every day, said the strike was frustrating.

"Everyone has to work overtime usually, it's not just the train drivers," she said.

Amy, who also catches the Parramatta train daily, agreed.

"I think if they're being treated poorly they're in their rights to ask for change, but I mean if they're talking about overtime, it's part of the job sometimes and you [have] got to deal with it."

Marg Prendergast from Transport NSW said there were buses on standby if stations became too busy.

Ms Prendergast told Channel Seven the Bankstown Line and the Airport Line were two big areas for concern, and commuters were warned to allow plenty of extra time if they were catching a flight on Thursday.

Due to the industrial action on the train network, alternate transport routes were expected to be busy as commuters opt for buses, cars or ferries to get to work.

Meantime, the Fair Work Commission will be hearing three applications jointly on the Rail, Tram and Bus Union's industrial action from 8am.