SA Police say brake failure and driver error will be considered as part of the investigation into yesterday's crash at the bottom of the South Eastern Freeway.
Nine people were taken to hospital following the crash at the intersection of Portrush and Cross roads at Glen Osmond about 3:45pm on Sunday.
Today Superintendent Bob Gray said investigators were yet to talk to the 60-year-old truck driver from Queensland, who remains in hospital with non-life-threatening injuries.
"We're doing a thorough investigation into this matter as you could imagine," he said.
"We haven't been able to speak to everyone that we would like to at this point in time."
Superintendent Gray said he had seen vision of the smoke coming from the truck as it descended the freeway, which would form part of the investigation, as would brake failure and driver error.
He did not rule out whether charges would be laid and said there would be further announcements.
"I would also like to remind drivers that are descending the freeway in a heavy vehicle that from Crafers to the bottom of the freeway there is a 60-kilometre speed limit, that's done for the safety of people at the bottom of the freeway," Superintendent Gray said.
"So, I remind truck drivers to select the right gear.
"Please just be responsible."
'It's a miracle'
Superintendent Gray said the construct of the intersection was not a police matter, but that they were interested in any measures that would improve road safety outcomes.
He said it was a miracle everyone involved in the crash survived.
"Unfortunately, it is a location where historically there has been bad outcomes and we're just very fortunate that we got what we had yesterday."
Engineering problems
There have been several fatal crashes at the intersection over the years, including the death of a 41-year-old truck driver in 2014, and the death of a 42-year-old man who was waiting at a bus stop in 2010.
Their deaths were the subject of a coronial inquest, which recommended lower speed limits for heavy vehicles and tougher penalties for drivers who do not use a safety ramp.
A third arrester bed has also been recommended.
Premier Peter Malinauskas said it had not been built due to engineering difficulties.
"This is something that has been looked at closely. I understand there was something in excess of 10 sites that were examined as potential locations for a third arrester bed, but the practical difficulty of building one of these is apparently very, very hard," he said.
"We're talking about a lot of complexity, let alone cost [although] I don't think cost is so much the issue here as I think the physical constraints in terms of which we are operating in the location."
Mr Malinauskas said he would meet with the Department of Transport and cabinet today to discuss the crash and whether a third arrester bed should be reconsidered.
"There has been an exhaustive piece of work. It's probably worthy of re-examination, but we probably also want to see what the cause here was ... just to make sure that any decisions we make in a policy sense are rationally informed by what we've learned out of the accident."
Department of Infrastructure and Transport chief executive Jon Whelan said the $75 million in funding had been secured to help implement further safety protocols.
He said that could include a third arrester bed.
"That will be IT (information technology) as well, alerting drivers if they do lose their brakes or if they're over-speeding," he said.
"And we'll also investigate options for further arrester beds or what we call catch-wire arrester beds.
"It's a very complex and tight section right down at the bottom of the freeway."
Mr Whelan said more than 50,000 vehicles used the freeway every day and roughly 10 per cent of those were heavy vehicles.
Local MP Dan Cregan has called for heavy vehicles to be removed from the corridor altogether.
He said if that were not possible, he would support any other alternatives that could be provided, including a third arrester bed.
"I acknowledge the associated cost and engineering risks, but believe an engineering solution would require a commitment of approximately $40 million," he said in a letter to Transport Minister Tom Koutsantonis.
