Trains to Sydney are operating to an amended timetable and passengers are advised to expect an extra 13 minutes' travel time.

Tuesday is a 'go slow' day, meaning trains will run at a maximum speed of 60 km/h.

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Festus Kimutai was travelling from Wollongong for an appointment and was concerned about making it on time.

"I was a bit confused when I saw the news [about the industrial action]... and I was worried I might not travel today," Mr Kimutai said.

Graham Hill, who was travelling to Parramatta for work, said the action just meant his journey took a bit longer.

"People are pretty tolerant if you're late because of industrial action," Mr Hill said.

Industrial action will continue through the week and Mr Hill has to travel again, but does not plan to make alternative arrangements.

"Things happen, you've just got to tolerate it, I guess. It's fairly infrequent," he said.

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Another passenger, Patricia, was travelling for leisure and said the disruption was frustrating, although it must be more so for people commuting for work, appointments or school.

She said the train was not running to Bondi Junction so she had to go in to Central and change there.

The Rail Tram and Bus Union is taking industrial action over the New Intercity Fleet, which it says is unsafe because drivers will use cameras rather than make physical checks to ensure no one has fallen between the platform and train.

The new fleet of trains is destined for the South Coast line but the dispute between the union and the government has delayed it.

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