AFTER a 20-tonne crane collided with a family car, a mechanical engineer has recommended some changes to speed limits for cranes.
Dr Robert Casey told Brisbane Coroners Court most crane accidents involving "wobbling and snaking" happened when vehicles were travelling faster than 60kmh.
He gave evidence on Wednesday, at the inquest examining the death of Christine Leonardi and her six-year-old son Samuel.
The Leonardis died after the crash near Toowoomba in September 2013.
On Tuesday, former crane driver Rodger Hannemann said the Franna AT20 crane driver began fishtailing "significantly" side to side before the crash.
He thought accelerating would apply more hydraulic pressure and help him regain control.
But he ended up hitting the Leonardis and smashing through a fence and trees.
"In that situation, where you're literally fighting for your life, what you perceive and what actually happens aren't necessarily the same things," Dr Casey said.
He was not critical of the driver, but said accelerating was not the best idea in situations like the one Mr Hannemann encountered in 2013.
"In all likelihood, it made the situation worse."
He said an 80kmh limit for cranes should continue only if electronic stability systems were fitted to cranes, and drivers were trained in how to handle instability.
But even a 60kmh limit would not be a panacea.
"You can still get instability, if you hit a big enough bump for example," Dr Casey said.
Counsel assisting the coroner Peter De Waard said crane maker Terex had suggested electronic stability programs were not commercially available, so would have to be developed.
Dr Casey said the mechanical hardware needed to implement the stability system was similar to computer technology used for ABS braking.
The inquest on Thursday will hear from the Department of Main Roads and Transport, and the Office of Industrial Relations, about issues including licensing and codes of practice for crane operation.
Haywire cranes could kill a 'group of citizens': inquest
A CORONER has questioned whether cranes should be allowed to drive through city centres amid fears an uncontrollable crane could "wipe out a group of citizens".
The inquest examining the death of Christine Leonardi and her six-year-old son Samuel has entered its second day in Brisbane.
Mrs Leonardi and her son died after a collision with a 20-tonne crane near Toowoomba in September 2013.
The crane in the fatal Toowoomba incident, after colliding with the Leonardi's ute, continued for some 60m, smashing through a fence and trees.
Coroner John Hutton asked on Wednesday whether cranes should be allowed to drive in city centres.
The inquest previously examined whether cranes should be put on floats, instead of driven on public roads.
Using a float would usually add extra time and labour costs for businesses, but Coroner Hutton said "citizen safety is paramount".
He added: "Employment is to the advantage of the state … and safety is to the advantage of the state."
The inquest at Brisbane Coroners Court heard discussion about whether the Franna AT20 crane experienced a "death wobble".
On Tuesday, the court heard crane driver Rodger Hannemann was unable to control the crane as it "fishtailed" or moved sideways before the crash, for reasons unconfirmed.
Dr Robert Casey, mechanical engineer and UniQuest automotive forensic investigator, gave evidence on Wednesday.
He said the New England Highway road section where the crash happened was ordinary.
"The road to me looked unremarkable," he said.
The crane in question was "for all intents and purposes" brand new, he said, having covered only about 400-500km.
"Everything seemed to be behaving normally" before the September 2013 crash, Dr Casey said.
The crane veered laterally, then went into the oncoming lane.
Dr Casey said the crane wheels left the road, and the machine went onto a verge, over an embankment, and came to rest in a field.
The crane's steering involved delivery of high pressure oil being delivered to cylinders.
"It was extremely easy to turn the wheel … you could do it with one finger if you wanted to."
Dr Casey found no oil leakage or damage in the crane cylinders when preparing an earlier report on the crash.
He said the crane involved gave little feedback to drivers.
The inquest was also examining whether speed limits for cranes should be altered, and how drivers ought to control wayward cranes.
"Speed never makes instability better," Dr Casey said.
The court also heard US manufacturer Terex was developing a crane with ABS brakes.
The inquest continues.