Police were at the crash site and a Greytown fire crew that arrived at the scene was stood down. Mr Robinson said the car seemed to have veered into roadside vegetation before the woman lost control of the vehicle and struck the low wall. No other vehicle was involved.
"The car was upside down in the middle of the road on its roof and she was still in the vehicle with moderate injuries, nothing too serious though. She was lucky."
The stretch of road was briefly closed at the Lincoln Rd intersection.
Garry Baker, operations manager at Carterton District Council, said the car had struck a roadside underpass wing wall, which flanked a pipe carrying the main Carterton water supply to the town from the Kaipatangata Stream.
He said the collision had left the water main unaffected but an air valve atop the pipe was damaged and would be replaced.