Former SA transport department bureaucrat Luigi Rossi proposes elevated motorway for South Rd

A former senior Transport Department bureaucrat has pitched an alternative design for the South Rd upgrade, and says it could save more than $1bn.

A 4km “Highway in the Sky” is the centrepiece of a bold pitch to alter the design of the final stage of the North-South Corridor project.

Former senior Transport Department bureaucrat Luigi Rossi, who has guided some of the state’s biggest infrastructure projects, is spearheading a new vision for the final 10.5km stretch of South Rd upgrades from the River Torrens to Darlington.

He claims his design would shave $1.1bn off the state government’s current $9.9bn budget, bring forward the completion date by up to 18 months, create extra jobs and save properties planned for demolition.

Luigi Rossi is proposing an elevated motorway from Cross Rd to Ayliffes Rd. Supplied by Luigi Rossi & Associates

The idea involves a 6km tunnel from the River Torrens to just before the South Rd Overpass at Cross Rd, connecting to a 4km elevated “Highway in the Sky” motorway extending to just before Ayliffes Rd.

Mr Rossi, who managed the building of the Heysen Tunnels, Northern Expressway and the South Rd Superway before leaving government in 2016 and establishing his own consulting firm, described his proposal as the “boldest and most imaginative piece of infrastructure ever envisaged for South Australia”.

“A key element is the proposed elevated motorway, ‘Highway in the Sky’,” he said.

“This engenders excitement, imagination and a driving experience that enlightens you as you drive across the clouds towards the city skyline. It will generate interest from all over the world.

“One of the fundamental elements and primary benefits of the concept design is to reduce the acquisition of properties and, where possible, only acquire properties that currently front South Rd.”

Artist's impression of the elevated motorway. Supplied by Luigi Rossi & Associates

Mr Rossi said his design had been independently costed, and would deliver major savings compared to the government’s current approach because it included one tunnel with two lanes in each direction rather than two tunnels with three lanes each way, and would require fewer property acquisitions.

He said it could be completed in early 2029, up to 18 months earlier than the current 2030 time frame.

The state government’s current design involves two tunnels and a mix of surface and lowered motorways.

In Mr Rossi’s plan there are interchanges at Sir Donald Bradman Drive and Cross Rd, and there are no lowered motorway sections, which he described as expensive and a barrier to east-west connectivity.

Map showing Luigi Rossi’s proposed tunnel and elevated motorway. Supplied by Luigi Rossi & Associates

However Transport Minister Corey Wingard said similar designs to Mr Rossi’s had already been considered, but failed to deliver the benefits of the government’s preferred “hybrid” design.

“While on the face of it, this idea may appear to hold some merit, it is already behind the times and outdated, with an elevated motorway investigated in detail and rejected because it failed to provide the benefits to the community of other options,” he said.

“If built it would be an imposing structure, sitting above South Rd for a length of 4km, creating a noticeable barrier between east and west, and frankly it would be an eyesore for local communities south of Cross Rd.”

The government will release its reference design, providing more detail about precise tunnel exit and entry points, later this year, and has already issued acquisition notices to affected residents and businesses.

Luigi Rossi pictured at the Northern Expressway during his time working in government.

SA Freight Council executive officer Evan Knapp said while Mr Rossi’s plan had some merit, it risked even further delays to the project.

“It appears to offer similar benefits to the current two-tunnel proposal,” he said.

“But the risk lies in making major changes at this point in time and throwing out a couple of years of work and starting again. At this point in time starting again really brings in genuine risks of missing that 2030 time frame and we’ve already suffered six years of delay.”

However Mr Rossi said it was more important that the multi-billion dollar project delivered the greatest value for money to taxpayers.

“If we can cancel a $90bn defence contract, then I am certain we can pause to reassess and consider the merit of an alternative motorway design, especially as we have not signed any contract to build anything.”

Mr Rossi’s single tunnel would be complemented by land-use changes along that stretch of South Rd, to enable medium-density housing of up to three storeys, and greater retail activity integrated with open spaces for cycling and walking.

Luigi Rossi is proposing major changes to South Rd development as part of his tunnel and elevated motorway design. Supplied by Luigi Rossi & Associates

The elevated motorway would feature an “extradosed” bridge design, with short pylons and cables set at low angles.

“An extradosed bridge is an economical and efficient solution to handle a high demand of traffic volumes in an urban environment without causing social dislocation and division, as caused by lowered motorways,” Mr Rossi said.

Mr Rossi will host community forums for local residents and businesses on October 12 and October 14 at the Thebarton Community Centre and Tonsley Hotel.

It is not the first time he has floated a grand idea to transform the state’s transport infrastructure. In 2018 he proposed a $1 billion fast rail link from Adelaide to Mount Barker to support the soaring population growth in the Adelaide Hills.

Originally published as Former SA transport department bureaucrat Luigi Rossi proposes elevated motorway for South Rd