Blackbutt resident Bob Cooper works as a volunteer at the Sydney Tramway Museum in Loftus every Wednesday, catching the train up and back.

In the afternoon he catches the southbound train that arrives at Sutherland at 3.55pm and said that, since the October introduction of the new rail timetable, that train was always packed until it reached Thirroul.

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"Every week since this new timetable has come in we've got to stand as far as Thirroul," Mr Cooper said.

"It just gets so crowded. It's not only us, there would be about 15 people in each of the vestibules that would be standing."

He said the issue reached a head at Sutherland last Wednesday.

"There were actually people left behind last Wednesday week because it was just overcrowded to blazes," he said.

"People just couldn't get on the train. There were strollers, there were pushbikes, people with luggage who had it on the seats because there was nowhere else for them to put it."

Mr Cooper believed a large part of the problem was the limited number of carriages on the southbound train.

He said there was an eight-car set that came up from Wollongong and that, when it got into Central, was split into two four-car sets, one of which arrived at Sutherland at 3.55pm.

A Transport for NSW spokesman said that last Wednesday afternoon there was a police operation under way in the Sutherland area as well as a self-harm incident in Miranda that could have created delays or had an effect on the number of people trying to catch the train.

The spokesman did not say whether the government had received previous reports of overcrowding since the new timetable came into effect.

However, he said the train service at Sutherland was sufficient.