Major works will swing into action today on South Australia's most complex road project in history - the South Rd Superway.

South Australian Transport Minister Patrick Conlon will today join Federal Member for Port Adelaide Mark Butler to observe the start of major works on the $812m project.

"When completed, Adelaide motorists will have a non-stop route between Port River Expressway and Regency Road and I am very pleased to see major work starting today," Minister Conlon said.

"This South Road Superway is the single biggest investment in a South Australian road project in the history of the state,

"In the context of the Federal Government's Nation Building Program, this project is about enhancing key road networks, to reduce congestion and improve transport efficiency," Minister Conlon said.

The South Road project will feature a new 2.8 kilometre elevated roadway between Wing Street and Taminga Street on South Road, and a new service road, with signalised intersections at major junctions.

The project will also substantially upgrade local roads to improve access, and improve and realign local drainage systems.

Mr Butler said the project would alleviate congestion and improve safety on the transport network in and around Adelaide.

"South Road is a key access route to the Port of Adelaide and to the regions north of Adelaide - it serves a significant industrial area," Mr Butler said.

"One issue facing the corridor is urban congestion, with road traffic expected to double by 2031. The Superway project will address this, while improving safety for pedestrians, cyclists and motorists."

The South Road Superway project is estimated to cost $812 million, with the Federal Government providing $406 million and the South Australian Government providing $406 million.