While he was a bit shocked, he was more worried about whether he had hit anyone else, he said.
It was the first time he had driven that particular truck.
The crash stopped traffic for more than an hour because there was no alternative route.
Three or four cars were thrown from the top level of the unit, and while the rest remained on the trailer, they were all damaged.
Mr Elley said the cars and the trailer were write-offs, but the truck might be salvageable.
Taihape police Sergeant Mark Toms said the crash took five hours to clear up. The road was opened to one lane about an hour after the crash, but was not opened fully until about 2.20pm.
A heavy haulage truck from Wanganui was called in to remove the cars and the trailer from the road. Fire and ambulance services also attended.
Mr Toms said the road was dry and the weather clear at the time of the crash, and the driver tested negative for alcohol.
The crash was still under investigation, and police would speak to witnesses before deciding if any charges would be laid, he said.