Fatal crash puddle clue
A JURY of 12 Clarence Valley residents sat in Grafton District Court yesterday listening to experts discuss the danger of ruts on the Pacific Hwy as they attempted to paint a picture of what caused the double fatality on the highway at Tabbimoble on March 12, 2010.
Garry Connelly, 61, and his wife Monica Connelly, 64, from Highland Park, Queensland, were killed in the head-on collision and a young man from the Valley is on trial charged with two counts of dangerous driving occasioning death as a result.
His identity is protected by law because he was a minor at the time of the crash.
Physicist and collision reconstruction expert Gavin Lennon told the court how ruts or divots form on roads where traffic flows. This, the court heard, would cause puddling during wet periods.
Mr Lennon described the phenomenon of "drag" in which a vehicle is slowed when it rolls across anything that is softer than the original surface.
He described "asymmetric drag", in which one side of a vehicle experiences significantly more drag than the other side.
"This would act to rotate the vehicle ... it would slow one side down more than the other (and rotate) even though there had been no turn of the (steering) wheel," he said.
Mr Lennon said another phenomenon known as aquaplaning or hydroplaning, in which a car loses traction with the road and effectively glides across the water, may have been involved in the Tabbimoble crash.
The court heard that if the front right-hand tyre of the young man's car hit a puddle at a speed above 90kmh it may have caused the car to rotate to the right and into oncoming traffic.
Adding to this rotating scenario was evidence the rear tyres of the 1993 Commodore had "less than the regulatory minimum" of tread on them, which meant, said two expert witnesses, the back of the vehicle would be more likely to lose traction and pull to the left.
Traffic engineer and road safety consultant Alan Joy said there was no indication that driver-related factors contributed to the crash although he conceded under questioning from Crown Prosecutor David Brack that the young man could have hit a puddle with his left wheel and overcorrected his steering into oncoming traffic on the right.
Mr Joy said it was a human reflex to correct steering when it was suddenly pulled to one side in water-drag situations.
"But what do you do when you are in those situations ... you slow down don't you," Mr Brack said.
"Yes, I've being doing this 32 years," Mr Joy replied.
The court heard the young man, who was a P-plater at the time, had a clean driving and criminal record. A former teacher and current employee testified to his honest and quiet character. The trial continues today.