The Kamilaroi Highway south-east of Narrabri is now undergoing works to increase safety for motorists.
The first stage of work will be on a four kilometre section starting at Turrawan Road, travelling south-east.
This will include installing rumble strips, a centre barrier, removing roadside hazards and widening the road.
Parliamentary Secretary for regional roads and infrastructure Chris Gulaptis said this would "aim to prevent head-on crashes and reduce the severity of crashes should a motorist leave the road".
Works will be carried out between 7am-6pm from Monday to Friday, and between 7am-1pm on Saturdays.
Changed traffic conditions will be in place for the safety of workers, including a reduced speed limit of 40 kilometres per hour during work hours.
The $22 million upgrade is funded through the state government's Saving Lives on Country Roads initiative, which Barwon MP Roy Butler said was "vitally important".
"People living in rural NSW make up one-third of the state's population, but sadly, two-thirds of all road crash fatalities occurred on country roads," Mr Barwon said.
"A number of workers leaving the mines after long shifts use this stretch of Kamilaroi Highway. It's important that we make sure it's safe to use in all conditions, day and night, to make sure they get home to their families safely."
The work is expected to be finished by mid-2020.