Three people remain in Dunedin Hospital following Sunday's head-on crash, including a child who, police said, was wearing a lap belt and not secured in a booster seat as legally required.
The woman, believed to be in her 90s, drove more than 1.3km in the southbound lane of the Southern Motorway after driving the wrong way north along the Abbotsford exit on Westland St, about 6pm.
Heather Heaps, who has lived in Westland St for 23 years, said she once saw an older female driver head the wrong way along the turn-off before turning around on the motorway.
While the turn-off exit included No Entry signs, she and fellow resident Callan Gaut believed signs were needed at the entrance to the street.
Mr Gaut, who has lived in the street for four years, had seen cars speed up as drivers mistakenly thought they were heading on to the motorway.
''I have seen quite a few accidents when they see the signs at the last minute.''
He had also seen other drivers try to turn left from a traffic island into the motorway exit, and believed the signs might be obscured.
''If you are hugging left there you can't see the signs from the driver's side ... It would be a hell of a smash if someone was trying to go up that way.''
New Zealand Transport Agency senior safety engineer Roy Johnston said the agency would consider whether changes were required to signage or lighting following completion of the police crash report.
NZTA reviewed signage of the site in June 2012, he said.
Senior Sergeant Alastair Dickie said the signage to Westland St was ''very clear''.
''I haven't heard of too many motorists who have done what she did.''
Police received multiple calls about the woman's driving.
''It was an accident waiting to happen, and it did.''
Police estimated she was driving between 60kmh and 70kmh in the right-hand lane when she encountered a 4WD and a car travelling south in the 100kmh area.
''The car that got hit was behind the 4WD and couldn't see her coming. She came up to the first two and they parted and she came through the middle and hit him,'' Snr Sgt Dickie said.
He was disappointed the child in the other car was not in a car booster seat as required by law for children under 7.
