Brake failure could be to blame for an out of control freight train, that narrowly avoided disaster at Unanderra.
The 40-wagon train reached speeds in excess of 100km/hr on Saturday, before quick thinking rail staff had it diverted to an uphill siding yard.
It's since been taken to Port Kembla, where rail officials continue to investigate the exact cause.
“The incident has been reported to the relevant rail safety regulators ... who will be investigating. ARTC will also investigate the incident,” said a spokesperson from the Australian Rail Track Corporation.