South Australia has its first elevated roadway as one of the state’s most complex engineering road construction projects moves toward substantial completion.

Following the opening of southbound lanes in January, the northbound lanes of the South Road Superway were opened to traffic last week, meaning that the $842 million project – the biggest single road investment in the state’s history – is now substantially complete.

Representing the second stage of a five-year plan to deliver a non-stop north-south route throughout Adelaide, the new road delivers an upgrade of a 4.8-kilometre section of South Road freeway grade and includes a 2.8-kilometre elevated roadway which runs over the existing roadway from the Port River Expressway to Regency Road. It passes over the Dry Creek to Port Adelaide railway, Cormack Road, Grand Junction Road and Days Road with exits at Grand Junction Road and Days road.

The Superway is elevated by 68 piers and includes 2,201 segments supported by 740 CFA piles and 68 pile caps.

South Australian Department of Planning, Transport and Infrastructure (DPTI) chief executive Rod Hook said the new road will cut travel times by up to seven minutes for the 45,000 vehicles that use the relevant section of the road each day.

“The elevated structure will improve safety and efficiency of freight transport, reducing the impact of peak hour traffic congestion” Hook said, adding that pedestrians and cyclists would be accommodated at ground level and on local roads,” he said. “Improved connections and service roads under and parallel with the Superway will provide access to properties and local roads along the existing South Road alignment.”

Drilling commenced in early 2011, with around 2,750 employment positions being created during construction.

The project was completed by the Urban Superway Joint Venture comprised of John Holland, Macmahon Contractors Pty Ltd and LEED Engineering & Construction Pty Ltd.