Shoulder sealing to the stretch of the Birdseye highway between Cowell and Cleve are well underway, with council expecting works to be finished by the end of the month.
Cleve District Council Mayor Phil Cameron said works had officially begun in the last two weeks.
"They've been doing a good job, it's progressing well," he said.
"They are just doing shoulder sealing to make the road wider...the rail closure is one aspect of that and the T-Ports bunker site is another."
The $2.5 million upgrade was announced by the state government in late 2018 after advocacy from the council to cater better to heavy truck movements.
"The road between Cowell and Whyalla had some shoulder sealing done before Christmas, but they decided not to do this one during harvest," said Mr Cameron.
"We reckon they're about halfway, it's going pretty well to schedule.
"They had to get more stockpiles of materials...they're putting out a couple thousand tonne (of gravel) a day.
"There are speed restrictions when they're working but it doesn't delay the trip too much.
"It should be done by the end of February." The works are being completed in 15 kilometre stretches, with gravel first laid before it is trimmed and then sealed.
Mr Cameron said he had not yet heard any updates regarding the Cleve-Kimba road, which is also due to be upgraded and the speed limit reinstated to 110 kilometres per hour.
It was one of eight roads across the state to have the speed limit reduced in 2017 to 100km/h.
This step was taken after the highway was deemed high-risk because of crash statistics.