Jackson Transport manager John Jackson said he was glad to discover his driver of 10 years was unharmed.
"By the looks of things, he is a very lucky man," he said.
Constable Marty Lack said persistent rain had fogged up Mr Martin's windscreen, creating difficult driving conditions as he travelled north on the wet road.
"He had attempted to wipe his windscreen with his hand, before the truck went off the road for a moment and slid down the bank.
"He said he was only going about 20km/h," he said.
Mr Martin said he was feeling a bit shaken.
"I might have to take a day off work to steady the nerves a bit," he said.
Crash site landowner Polly Macdonald was called by a friend to go and assist.
"I was happy to hang up my hammer and come out and help," she said.
She has witnessed a few crashes on the winding roads near her property in the short time she has lived in the area.
"We've only been here two years and I've seen about four crashes, so I suppose that's a few," she said.
The road was closed yesterday afternoon while the truck was removed.