Experts examined third South-Eastern Freeway arrester bed eight years ago

It would be expensive, but a flyover at the bottom of the freeway could be a solution to stop catastrophic truck smashes – as experts debate a third arrester bed.

Engineers from an interstate university were engaged eight years ago to investigate the installation of a third arrester bed on the South-Eastern Freeway downtrack.

The Department of Infrastructure and Transport has told a parliamentary committee it worked with the University of Queensland to develop a “catch-wire system” after an inquest into a fatal crash involving an out-of-control truck.

Premier Peter Malinauskas said the installation of another arrester bed would be re-examined after another serious accident involving a truck on Sunday left nine people in hospital, including its driver.

Chief executive Jon Whelan told the Budget and Finance Committee on Tuesday his department would look again at various options for an arrester bed closer to the bottom of the South-Eastern Freeway.

Emergency services personnel at the latest crash at the bottom of the South Australian Freeway. Picture: Keryn Stevens

“What we have made a commitment to, and what the Premier has made a commitment to, is that we will investigate an option for a third arrester bed or what we would call a catch-wire system,” he said.

“We will look for one that is between that existing arrester bed (beneath the Heysen Tunnels) and the bottom of the freeway.”

Another option could be a flyover at the bottom of the SE Freeway as one potential solution to the repeated crashes that occur at the intersection, one road safety expert believes.

But Scott Elaurant, the SA chairman of the Engineers Australia Transport Australia Society, said a “grade separation’’ such as a flyover would be expensive and difficult to fund.

He said federal governments had directed most road funding towards “congestion-busting” projects rather than on safety measures.

Dr Elaurant said a study would be needed to determine the correct design, but one option could be extending the freeway down Glen Osmond Rd, while Portrush and Cross roads joined up underneath.

“If you did that sort of grade separation, you would make that kind of crash virtually possible,” he said.

DIT executive director Andrew Excell said more than 20 options to improve safety were examined following two fatal crashes involving trucks at the bottom of the freeway in 2013 and 2014.

“We did extend the current safety ramp,” he said. “We widened it, we made it longer, we refreshed all the gravel, we improved the signage, we lit up the locations.

“We put a lot of effort into ensuring that the current safety ramp that is there is up to standard and can stop all trucks that are out of control down the freeway.”

Emergency services personnel at the latest crash at the bottom of the South Australian Freeway. Picture: Keryn Stevens

Mr Excell said the department “then looked at trying to locate a third safety ramp between the existing safety ramp and the freeway – the intersection at the bottom”.

“We did a lot of work with Queensland University in terms of modelling how trucks may enter it, because it’s quite a challenging and restricted environment,” he said.

“There are quite steep hills and then, of course, development starts and access points start to appear. There was lots of work.”

Mr Excell said the third access ramp would be included in a departmental review of the latest accident.

“There are a lot of operational issues with safety ramps because of the gravel, the kitty litter-style arrangement,” he said.

“If it (the third safety ramp) was located in the middle of the road there are operational issues like how do you control all the stones that get flicked across the road.

“To comply with standards we need quite a lot of space and length for that.

“If you look at the current safety ramp, it does take up a lot of space.”

Mr Excell said the department had worked closely with the RAA and South Australian Road Transport Association on improving the safety of the road, particularly driver education.