Transport industry officials fear an investigation into last week's double fatal crash on the South Eastern Freeway in Adelaide faces a lengthy delay after a coronial inquest was adjourned.
After sitting for several hours last Friday, deputy coroner Anthony Schapel made several speed limit recommendations for the Hills freeway then adjourned proceedings.
He is investigating the deaths of Tom Spiess, 56, and Jacqueline Byrne, 41, after an out-of-control sewage truck hit other vehicles at the base of the freeway.
Two other victims of the crash remain in a serious condition in hospital, one of them the driver of the truck.
Road Transport Association official Steve Shearer expressed concern there might be a long delay before the coronial investigation proceeded.
"Our understanding is it could be up to two years before that's called back on again," he said.
The transport industry is keen the investigation of the deaths be completed within months as a way to help prevent future accidents on the freeway descent into Adelaide.
"If that means that police need to be asked to give it number-one priority, then that's what should happen," Mr Shearer said.Union urges wider investigation of freeway accidents
Transport Workers Union official Ray Wyatt said the scope of the inquest should be broadened to look at other freeway crashes.
"I would hate to see any inquest restricted by time restraints," he said.
"They need the ability to be able to do it fully and professionally."
Mr Shearer supported widening the scope but said that must not be allowed to delay proceedings.
The South Australian Government said the inquest's timing was a matter for the coroner's office, which it said had acted swiftly after last week's deaths.
Opposition legal affairs spokeswoman Vickie Chapman urged the Government to do more.
"It's quite within the power of the Attorney[-General] to ensure resources are provided to advance the hearing of a particular case," she said.
"We are seeing deaths one year and final reports arriving in Parliament three years later. It's very disturbing."
From next Monday, speed limit changes will take effect for the South Eastern Freeway.
A limit of 60 kilometres per hour will be extended to all trucks and buses making the freeway descent into Adelaide.
Other motorists will face a limit of 90kph rather than 100kph for part of the down track.