Drivers are being advised to avoid the Monaro Highway at Fyshwick after a truck trailer overturned about 11.30am on Tuesday.
The truck was turning right from Newcastle Street onto the northbound on-ramp when the trailer, which appeared to be carrying wood chips, overturned and became separated from the vehicle.
A traffic light was knocked over in the incident, which also involved a small car.
Emergency Services Agency staff are on scene, and some warning signs are in place.
The drivers involved declined to comment on the accident.
Delays are expected into Monday afternoon as the trailer is removed.