Port Kembla train drivers John Anderson and Wayne Dunstan were killed early hours of May 19, 1998 when their National Rail Corporation Freight Service locomotive derailed after colliding with concrete debris on the Unanderra to Moss Vale line.

A section of the embankment, which also supported the old Illawarra Highway, had slid down during the night to cover the track.

The court heard demolition work undertaken to remove the deck of a redundant roadbridge over the railway line in 1997 had destabilised its supports, causing the old bridge to collapse on the line after two weeks of heavy rain.

The court also heard that no further engineering advice was sought before the work was performed to remove the old bridge.

The Rail Infrastructure Corporation (RIC) pleaded guilty to failing to ensure the railway was safe and without risk to workers.

In handing down his judgement, IRC President J Wright said he considered the offence to be of great seriousness.

"The actual and potential consequences of the risk being permitted to exist and persist were of the highest order," he said.

"Two tragic deaths resulted. It is conceivable that, but for the time of day when the collapse occurred, even more deaths could have resulted.

"The relevant risk was plainly foreseeable...simple, straightforward, well-known and, on the defendants case, well promulgated precautions, if observed and required to be observed, would have obviated the risk and avoided the accident and loss of life."

"Having regard to the maximum penalty for the offence, its objective gravity, the importance of general deterrence in respect to the offence, and the overall culpability of the defendant, the imposition of a substantial penalty is necessary."

Workcover Acting Executive CEO John Watson said he was pleased with the findings, but said "the tragic loss of life from this incident could have been prevented if a safe system of work had been introduced."