An incident that happened at the entrance to Newcastle Link Road is being investigated by NSW Roads and Maritime Services (RMS) when an oversized load became wedged on an off-ramp.
The heavy haulage truck was carrying a pressure vessel when it moved through the passage and became stuck on infrastructure.
The company involved was accredited and had an oversize load permit.
Police said the off-ramp would be closed all day.
In a statement the RMS said a truck transporting refinery equipment traveling eastbound struck a guardrail and became stuck on the M1 Pacific Motorway offramp to Newcastle Link Road at Cameron Park.
A removal operation ensued which caused the road to be closed well into the evening.
Detours were set up and motorists were asked to exit the motorway at George Booth Drive.
The National Heavy Vehicle Regulator (NHVR) has warned operators to avoid that particular section of the motorway.