Ms Bruce hasn't been seen since her silver Toyota Corolla hit a roadside barrier about a kilometre north of the Old Cleveland Road exit about 12.10pm on Wednesday, April 29.

After leaving her car the 45-year-old got into the ute, leaving personal items behind including her phone.

Police have grave concerns for her wellbeing and believe the driver of the ute, which wasn't involved in the crash, could help with their investigations.

"There's every chance according to our information that person did witness that accident,"  Detective Inspector Rod Kemp said.

"They could well be good Samaritans that have stopped to assist and taken her on from the scene of the accident.

"We are aware there's another vehicle stopped to assist as well, so we're pleading with those people to come forward and assist."

Investigators are also appealing for any witnesses to the crash to contact them.

They have little to go on because CCTV footage of the ute heading north after the incident isn't clear enough to identify a number plate or even the gender of the driver.

No witnesses have come forward as yet but police are hoping heavy traffic on the motorway at the time meant a large number of people saw the incident.

Inspector Kemp said police were particularly concerned because the Springbrook woman's car hit the rail "in a hard fashion".

"She may well be injured, she may well not be but because it's so much out of character for her we have grave concerns as does her family," he said.

Inspectors have checked with hospitals in the area and scoured CCTV footage on the motorway and nearby exits.

Ms Bruce is described as about 165 centimetres tall with a slim build, brown hair and hazel eyes.

Anyone with information regarding her whereabouts is urged to contact Crime Stoppers on 1800 333 000.