The haul truck operator was trying to park next to a parked haul truck.
He misjudged and the rear left of his truck's tray hit the front right tray of the truck.
The NSW Resources Regulator said equipment operators had to check their surroundings before parking.
"Workers must ensure the correct separation distance between equipment is applied when parking and not rush to park up for breaks or shift end," it said.
"Park-up areas should be designed and constructed to drive through to prevent reverse parking and have adequate lighting and demarcation."
