The crash brought traffic to a standstill last night, trapping motorists for hours on the motorway.
Some desperate drivers abandoned their vehicles and walk to escape the gridlock.
One driver who had been stuck in traffic for more than three hours told RNZ “people seem to be panicking and trying to drive up the shoulder”.
Another stranded motorist waiting for four hours said people had started parking their cars and walking away across the motorway.
Elise Bailey told RNZ she’d seen more than 20 people, including some with toddlers, walk along the motorway and cross the median barrier into oncoming traffic.
The road reopened shortly before 11pm after the Serious Crash Unit had examined the scene.