About 4.15am, five wagons went off the tracks, preventing any passage of trains into or out of Goulburn.

An ARTC spokesperson said the independent rail investigator had completed its onsite investigation.

"Repair and recovery works have begun," the ARTC spokesperson said.

"No trains will run through Goulburn until recovery and rerailing works are completed."

Read more: 'We are in emergency' - Out-of-control train hit 107km/h near Unanderra station

A Goulburn Station worker said train services had been replaced by road coaches, meantime.

The ARTC was not able to confirm when normal services would return, but would provide updates throughout.