SA fatal crash speed limits to be cut

Speed limits are to be cut on parts of an Adelaide freeway after a high-speed smash in which a Transpacific sewage truck crashed into three stationary cars, killing two people.

An inquest into the two deaths on Friday was told the truck was travelling at 151.9km/h just before the crash at the major intersection at the bottom of the South Eastern Freeway on Monday.

As the road descends, the speed limit now changes from 100km/h to 80 then to 60 for vehicles with five axles or more.

Deputy state coroner Anthony Schapel has called for all trucks, regardless of the number of axles, to be subject to a 60km/h speed limit while coming down the steep freeway from the Crafers Interchange.

Road Safety Minister Tony Piccolo later announced such a cut for all trucks and buses and a reduction from 100km/h to 90km/h for light vehicles on another section of the freeway, to apply from September 1.

He denied the move was prompted by the coroner, saying they were the result of week-long discussions with SA Police and the Department of Transport.

Mr Schapel said he decided to begin, as soon as possible, the inquest into the deaths of two drivers, Thomas Spiess, 56, and Jacqueline Byrne, 41, because it was in the public interest.

The 28-year-old male truck driver, of Netley, and a 48-year-old woman, of Hahndorf, are in a critical condition in hospital.

The investigating officer, Brevet Sergeant Peter Light, told the inquest the Transpacific truck, believed to be fully laden with 8000 litres of sewage, had two axles.

CCTV footage relating to the truck's descent was played, including an excerpt which the sergeant said appeared to show the truck was out of control and lurching to the left.

He estimated that in the seconds before the crash the truck was travelling at 151.9km/h.

Mr Piccolo said the speed changes will create a more calm traffic environment and reduce the risk of fatal accidents on that stretch of road.

"I'm glad that the proposed action we're taking is consistent with the coroner's recommendations," he told reporters.