"We heard a loud screeching noise and saw a big puff of smoke," Jamie Gardner said.
"Two of us called for help and another two directed traffic.
" Crashes don't usually happen here, it's usually further up the road."
Fellow worker Hayley Bale said another truck driver had stopped to assist with his fire extinguisher along with an off-duty fire officer on a motorbike.
"It was lucky there no cars coming the other way when [the truck] crashed," she said.
Rotorua police Sergeant Chris McLeod said the truck and trailer unit was carrying one shipping container which held non-dangerous goods.
"It was travelling north, coming around the corner when, for whatever reason, it crossed the centre line and tipped on its side," Mr McLeod said.
"The commercial vehicle investigation unit along with the police will be investigating.
"It's still early but some of the things we will be looking for is driver fatigue, speed and the manner of driving."
Two cranes were used to upright the container and the truck and tailer.
The road was closed for about four hours with diversions in place at Jackson Rd and Kaharoa Rd.