With emergency services en-route, the 74-year-old grabbed a torch, ran outside in the rain - and was met with an awful sight.
"He was in a terrible state," he said.
"I was so worried about making him comfortable ... what I saw will stay with me for a long, long time."
He stopped his wife from coming closer to the crash and, a week later, still struggles to sleep.
It's the ninth crash at his property in 12 years - and he's at his wit's end, trying to make the area safer.
"We've had drunks, there have been medical events ... it's frustrating, to say the least."
Taking the issue up with the Waimakariri District Council saw the Tram Rd shoulder widened and the North Eyre Rd intersection revamped.
But Grieves said it's only made the problem worse.
"The cars now appear to be going faster around the bend, because it's so large and well covered."
Locals believe a steel barrier around the corner would make it safer for motorists but Grieves said they'd been told it's too costly.
