THE runaway crane that killed Christine Leonardi and her son Samuel in September 2013 struck her vehicle with such force it left it unrecognisable, a court has heard.
On the morning of September 16, 2013 Rodger Douglas Hannemann was driving a Franna AT20 crane southbound on the New England Hwy. Mrs Leonardi was driving her three children to school in Toowoomba.
A coronial inquest will investigate how the crane driver lost control of the vehicle - and what can be done to make driving cranes on public roads safer.
A pre-inquest conference in Brisbane on Tuesday heard as the crane drove slightly downhill around Top Camp it began to swerve.
The court heard witness and physical evidence showed Mr Hannemann began to brake but could not stop the swerving so he accelerated to try and regain control but the fishtailing increased.
He eventually lost control of the vehicle and collided with the Mrs Leonardi's Ford dual cab ute despite her efforts to avoid him.
Mrs Leonardi was killed instantly and her six-year-old son Samuel died in hospital days later. Her two other children were injured but lived. Mr Hannemann received minor injuries.
Peter De Waard, counsel assisting the Coroner John Hutton, told the court a chain cut through the driver's side of the car like a "potato peeler".
"The damage to Mrs Leonardi's vehicle was so extensive that the make and model of her vehicle were unrecognisable," he said.
Mr Hannemann will be called as a witness but has not previously engaged in a recorded interview with police.
The court heard the Franna AT20 drives differently from cars, buses, trucks and many other cranes. The inquest will investigate whether there should be a separate licence category for cranes, or this type of crane.
It will also examine whether the Franna AT20 crane should be limited to 80kmh as it is in NSW.
Mr Hutton said how Mr Hannemann reacted to the situation would be of importance to what changes he recommended.
"The question that begs here is why did he accelerate instead of decelerate," he said.
"That's probably the most vital question."
The inquest will be held in Brisbane July 11-14.