Adelaide's north-south road corridor is South Australia's most vital infrastructure project for creating jobs, Prime Minister Tony Abbott says.

Mr Abbott joined South Australian Premier Jay Weatherill to launch construction work on the $896 million Torrens to Torrens section of the corridor in Adelaide.

The upgrade, which stretches 3.7km from Torrens Road to the River Torrens, is expected to create 480 jobs during construction.  Mr Abbott said work on another section of the corridor at Darlington would also start in the coming months.

“Plainly, if we want to do the right thing by jobs and growth here in South Australia, the most important infrastructure project is getting a north-south corridor up to expressway standard by 2023,” he said.

Mr Weatherill said 90 per cent of the labour hours for the project would go to South Australians.

“Which is an incredibly important contribution to grappling with the challenges we face in our economy,” he said.

The premier said plans to complete the entire project had now been submitted to the federal government.

“It now becomes a question of reaching agreement about how we stage the rest of this north-south road corridor,” he said.

Torrens to Torrens will provide three kilometres of non-stop roadway along one of the busiest sections.

It also includes a two-kilometre section of lowered motorway, an overpass for a rail line, six intersection upgrades and improved cycling and pedestrian paths.