A semi-trailer loaded with general freight clipped power lines at the roundabout on Bulahdelah Way and Lee Street at about 8 last night which fell onto the rig and caught fire.
Around 40 firefighters from as far away as Cardiff took six-and-a-half hours to extinguish the blaze which destroyed the b-double and its contents.
It's understood the driver escaped injury.
A salvage operation is continuing with traffic down to one lane past the scene at a reduced speed limit of 60 kilometres per hour.
