A construction company working on upgrades to a highway north of Sydney has been fined $250,000 after one of its workers was crushed to death by a roller.

The 31-year-old labourer was on his second day on the job with Coastal Asphalt and Civil Constructions Pty Ltd on a road upgrade project near Newcastle.

He was helping to lay asphalt when a three-tonne multi-wheeled roller ran over him in January 2010.

The labourer was helping the operator of the heavy vehicle by using a hand-held spray can filled with diesel to periodically remove asphalt stuck to the roller.

A WorkCover investigation subsequently found the mid north coast company failed to properly train or supervise the man.

"This tragedy could have been avoided had there been the right instruction and the vehicle properly maintained," Finance Minister Greg Pearce said in a statement on Thursday.

Coastal Asphalt and Civil Constructions was one of several companies upgrading a stretch of highway known as The Lakes Way, Boolambayte, at the time of the tragedy.

The worker was spraying the stationary roller when the operator accidentally released the brakes, causing the vehicle to lurch forward and roll over him.

"Coastal Asphalt and Civil Constructions did not provide a safe way to remove the asphalt from the roller and the incident could have been prevented if the roller's built in diesel spray unit had been working," Mr Pearce said.

"This is a sad reminder of the need to maintain proper safety protocols."

Mr Pearce said WorkCover was working with the company to ensure the same mistakes are not repeated.

Coastal Asphalt and Civil Constructions pleaded guilty to a breach of the Occupational Health & Safety Act and was fined $250,000 by the Industrial Court of NSW, and ordered to pay court costs.