It is hoped the Stuart Highway between Adelaide and the Northern Territory will open to all traffic by the end of the week.
Freight has already started to move through still damaged sections of the highway between Glendambo and Coober Pedy in the north of South Australia.
Trucks can only travel at 20kmh during daylight hours for a long stretch of the highway, and one way only.
There is still water on the highway for long stretches in the 200 kilometre section.
This emergency measure is hoped to ease two weeks of critical freight shortages in the Northern Territory which has seen enormous detours through Queensland used.
Supermarket supplies in Darwin, the NT's major towns and outback areas have been badly hit.
Rail services are still a few weeks from being repaired from the devastating flash floods of several weeks ago from what experts are now calling a one in 200/300 year event.
Authorities hope to re-open the highway to high clearance 4WD vehicles from tomorrow and then open the highway to all traffic later in the week under restricted management conditions.
SA Premier Steven Marshall said strict conditions would be applied along a 600-metre section of highway, with a 20km/h speed limit and only one truck permitted to use the section at a time.
"We've been working hard with emergency services to re-open the highway as soon as possible, but we need to do it in a safe way that will not damage the road further," Mr Marshall said.
"There is still a huge amount of clean up work to be done but we are relieved to re-open the highway and see the community gradually transit through."
Mr Marshall said the Commonwealth had been asked for disaster support and he was hopeful of a response early this week.
The Australian Rail Track Corporation on Friday said crews had been working around the clock to repair damage at 18 separate locations and were now focused on the remaining six.
Most of these are in the Tarcoola region of SA which copped more than 200mm in one day.
Premier Marshall said his Government was doing everything it can to help support everyone affected by South Australia's recent extreme weather, from flying in vital supplies to cut-off communities, to sending rapid response teams out to assess damage.
MORE READING: First drone footage of the rail repair.
"No stone will be left unturned in our efforts to help our regional communities, who have been dealt a fierce blow with many extreme weather fronts over the last week," Premier Marshall said.
"While the rain has been a godsend for some of our farmers, it has been devastating for local communities who have been cut off because of closed roads, rail and other vital infrastructure."
Works to repair the vital rail connection between the east and west coast is expected to be complete in mid-February.
ARTC track repairs also involve the rail line heading north to Darwin which was also badly damaged by the heavy rain.
Perth is suffering from depleted grocery stocks with speculation Australian Navy ships might be called on to help.
Freight companies have been allowed to use three trailers and not the two to hook up to prime movers for trips across the Nullarbor.
RAAF plans provided an emergency food airlift to the Coober Pedy Airport last week.
A spokesman for ARTC said: "Following an extensive and detailed assessment of all track, ARTC can advise completion of the repair works is expected to occur by mid-February.
"This timeframe is consistent with initial updates provided to customers, stakeholders and the broader community.
"Our focus is to repair the line as quickly as possible, in the safest manner, to ensure operations can commence and freight can get moving."
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