The $252 million major re-railing upgrade between Adelaide and Tarcoola is nearing completion, with final contracts being awarded from this month.
Deputy Prime Minister Michael McCormack said the significant infrastructure project had created much-needed local jobs for South Australia and would provide a long-term freight productivity boost.
"As many as 180 workers have been employed on the project so far, with many of these located in regional South Australia, such as Whyalla and Port Augusta," the Deputy Prime Minister said.
"The main re-railing work is already done and dusted, paving the way for finishing works such as replacing wooden sleepers with new concrete ones to complete the project."
Finance Minister Mathias Cormann said the project was already significantly improving the efficiency and productivity of freight movements between Eastern and Western Australia, meaning businesses can get their goods to local and international markets faster.
"Re-railing this key section of the national rail network will allow heavier, more efficient freight trains to safely operate at faster speeds," Senator Cormann said.
"This is a major shot in the arm for our entire supply chain, particularly some of our key industries such as mining, which will be able to haul larger loads of their world-renowned products on more efficient trains.
"With some of the final tenders for remaining works to be signed as soon as next month, South Australia and the entire national supply chain will soon reap the benefits of the improved track."
Federal Member for Grey Rowan Ramsey said nearly 70,000 tonnes of Australian-made steel from Liberty's Whyalla plant was delivered as part of the upgrade.
The project involved upgrading close to 600 kilometres of standard gauge rail track between Adelaide and Tarcoola line by replacing 47-kilogram-per-metre rail with stronger 60-kilogram-per-metre rail, allowing for 25-tonne axle load limits.