The Federal Coalition Government has promised to duplicate the Augusta Highway between Port Wakefield and Port Augusta, if it wins the election.
They have committed $64 million to the project.
The Civil Contractors Federation of South Australia has estimated duplicating the 200km stretch would cost $1.2 billion.
Labour have labelled the announcement a sham saying the Liberal commitment would cover just 5 per cent of the overall cost.
The project would be book-ended by the planned Port Wakefield duplication and fly-over and a duplicated Joy Baluch AM Bridge at Port Augusta.