A former crash scene investigator has explained how different types of tyre marks are examined following the Hunter Valley wedding crash.
The coach was carrying 35 guests who had attended the nuptials of local football star Mitchell Gaffney and Madeleine Edsell at the Wandin Valley Estate on Sunday, and was en route to nearby Singleton when it rolled just after 11.30pm at a roundabout at Wine Country Drive near the Hunter Expressway off-ramp at Greta.
Ten people were killed and 25 hospitalised in the country’s worst road disaster in 30 years.
Peter Bellion, 58, who retired from Victoria Police in 2016 after a 30-year career, explained the different types of tyre marks investigators inspect in the wake of a crash.
“In a collision investigation there’s three main types of tyre marks you come across — rolling prints, tyre scuff marks and tyre skid marks,” he said. “There’s various forms of each of those, but they’re the three principle categories you look at.”
Mr Bellion said tyre scuff marks were the most common form seen in crash investigations. “A tyre scuff mark is left by a tyre or wheel that’s rotating in the forward direction, so there’s no real braking — [but] there can be braking — and sliding out to the side,” he said.
“The most common form of that type of tyre scuff mark is what’s known as a yaw mark. A yaw mark is a tyre scuff mark that’s curved in shape, which is basically what we’ve got in this situation. The telltale signs within that are things called striations, which are angular transfer marks towards the outer edge, normally at an angle, slightly forwards and out to the side.”
Investigators can tell from looking at those striations, “depending on the spacing between them and how much they’re angled forward or out to the side … whether a driver would still be under acceleration when leaving them”.
He added that large coaches like the one in the crash would have anti-lock braking systems, which leave characteristic tyre marks.
“If there’s a sudden, firm application of brakes, so much so that it invokes the anti-lock braking system, you’ll get what’s called little skip-type skids,” he said.
Meanwhile, a local business owner told the ABC on Monday morning that the roundabout where the crash occurred had been under construction for several months, with traffic reduced to one lane only.
“So it was a one-lane roundabout and they’re currently extending and doing road works on it,” Peta Hughes told ABC News Breakfast. “They’ve got barriers and the safety bollards and things up around there. It’s a 40km/h zone.”
Hunter Labor MP Dan Repacholi told the same program he did not believe the reduction to one lane would have contributed to the accident. “We drive around the Hunter roads every day of the week,” he said. “Those roads in that area are good roads. So I really can’t see that being an issue.”
Responding to suggestions that the roundabout curve was too tight, Mr Bellion said it did not appear to have been unusually dangerous.
“A lot of roundabouts you get that situation, before getting to the final part they do normally get a little bit tighter, particularly when you’re making a right-hand turn,” he said. “Generally for a roundabout of that nature, a typical design speed would be about 40km/h.
“In terms of causation the evidence will come out in court.”
Bus driver Brett Andrew Button, 58, faced court on Tuesday charged over the horror rollover.
Survivors and close friends said multiple passengers had expressed concern about the speed of the bus throughout the trip, and had urged others to return to their seats for safety.
Mr Button, who was charged with 10 counts of dangerous driving occasioning death and one count of negligent driving, allegedly said “fasten your seatbelt” to passengers just before the fatal moment, Cessnock Local Court heard on Tuesday.
The Daily Telegraph earlier reported that witnesses alleged Mr Button boasted to those on board through the internal microphone moments before losing control, “If you think that was fast … watch this.”
NSW Police Acting Assistant Commissioner David Waddell alleged the bus driver was travelling too fast.
“He entered that roundabout driving in a manner that was inconsistent with the conditions,” he alleged to reporters on Tuesday morning. “Obviously the speed was too quick for him to negotiate that roundabout, causing the vehicle to fall onto its left side and cause those injuries.”
Mr Button, who appeared in court in a black jumper and was supported by members of his family, sobbed as he was granted strict conditional bail. Despite prosecutors being “strongly opposed”, Magistrate Robyn Richardson noted the “onerous” conditions and said bail should not be denied as punishment.
“Mr Button has sat in court head down throughout these proceedings and it is clear to the court he suffers, along with the rest of his family,” she said. “Button is deeply linked to his community and has support here today … I note the stringent proposed bail conditions.”
Mr Button will next face Newcastle Local Court on August 9.
frank.chung@news.com.au
— with Clare Sibthorpe