Police Northern Communication Shift Inspector Willy Taylor said the woman believes she has crashed about 10m off the road down a bank, as she can hear traffic passing above.
He said she called her husband who in turn called emergency services.
"We are responding to a crash where the person in the motor vehicle has phoned her husband. She is unsure where she is and we are still trying to locate her."
Police, Fire Service and St John ambulance staff were all searching the area.
"We have made contact with her, but she is injured and dazed and cell phone reception is a bit sporadic."
The woman was tooting her car horn, he said.