"She phoned her husband to say she was injured, but didn't know where she was, so he called us and it was every man and his dog jumping in their cars and running around looking for her."
There were six police cars carrying nine police officers, two fire appliances with up to 14 people aboard, one ambulance and a paramedics vehicle - plus the woman's husband - scanning the road sides.
The woman had a minor head injury which meant she was confused about her surroundings, said Mr Roberts.
"If she didn't have her phone on her it could have been a lot worse, but all she was saying was she could hear trucks and cars going past but she couldn't give her location.
"She was instructed to intermittently beep her horn and so were we, but one policeman just happened to stop and have a look and there she was."
He scrambled down the bank and stayed with the woman until medics and fire crews arrived to treat her and winch her out in a stretcher about 11.40am.
"If he hadn't stopped there, we are not sure we would have seen her. It's just amazing that she didn't have more serious injuries."
She was taken to Bay of Islands Hospital for treatment for the head injury, and was understood to be in a stable condition last night.