South Australian authorities estimate it will take 12 days for floodwaters to subside on the Stuart Highway and for restoration works to begin.
The Stuart Highway connects Adelaide and Darwin and has been closed for about a week between Port Augusta and Coober Pedy, cutting off road freight to remote parts of South Australia and the Northern Territory.
South Australia's State Emergency Service (SES) says options are being explored to pump the water away so the road can open sooner.
"The Stuart Highway remains closed at Glendambo with water 400 millimetres deep over the pavement and we expect it to be at least 12 days until the water has subsided and restoration works can commence," SES chief officer Chris Beattie said.
"Engineering options are being explored to accelerate this time frame by draining or pumping the water."
Works to repair the railway lines connecting South Australia with the NT and WA are not expected to be complete until February 17.
Man wants to see wife before heart surgery
Milivoj Perkich say he is the most desperate man stranded in Coober Pedy because of the flooding.
Mr Perkich, 82, is hoping to get to Melbourne by Friday, when his 79-year-old wife, Pamela Sinclair, is scheduled for open heart surgery.
He had been driving with his daughter Renae and six-year-old granddaughter Tanami from Darwin to Melbourne when the highway closed.
"Unfortunately, Mother Nature has done its bit and we weren't able to go through," Mr Perkich said.
"I've been here for nearly eight days. I'm a very desperate man.
"My wife this Friday she has to go to Melbourne for open heart surgery — she has leaking valves."
He is not sure she will survive the operation.
"It could go either way," he said.
"She is going to go to the best specialists at Alfred Hospital, but you never know — it's a major operation.
"I didn't shake her hand — nothing, zero.
"I feel like crying but I don't, but I'm just hoping she will come out, that's my concern here."
Call for more flights from town
Police have told him it is too dangerous to try to travel south another way.
He wants more flights put on to Adelaide, in addition to the regular three-a-week run by Regional Express.
"I just feel so useless," he said.
"I cannot help my wife, I cannot help my daughter, I don't know, I'm just lost in space."
Premier Steven Marshall on Tuesday said the state government had chartered "every available aircraft in the state at the moment to help with the overall response to this new major emergency declaration".
The ABC has also spoken to several people stuck in Coober Pedy.
One man had just sold his house in the Northern Territory and was in the process of moving before the rain came.
Another was moving items between homes in the NT and SA.
Tonnes of food and other supplies started arriving in Coober Pedy from Adelaide yesterday.
Coober Pedy has mostly been spared from heavy rain, unlike the APY Lands or Port Augusta.
