The boilermaker was repairing the bucket of the large excavator at the time of the incident.
The NSW Resources Regulator said the light vehicle had slowly rolled from its parked location.
"The vehicle narrowly missed the boilermaker as it rolled," it said.
"The vehicle was parked for some time before the incident occurred."
The regulator said that when setting up work areas, vehicle park-up areas should be located where vehicles could be parked fundamentally stable and clear of work areas.
"All workers should confirm their vehicles are parked fundamentally stable before leaving the vehicle," it said.
"Vehicle operators should daily check the function and operation of braking systems."