The winding Kawarau Gorge section of State Highway 6 is to get $250,000 worth of curve warning signs and safety barriers.
Queenstown and Central Otago police regularly respond to complaints from members of the public about dangerous or inept driving by other motorists on the road.
In the last five years, nine people have been seriously injured on the stretch between Pearson Rd, at the Cromwell end and the Crown Range turnoff at the Queenstown end.
No-one was killed in that period but the New Zealand Transport Agency had recorded 104 crashes, although this year's data is incomplete.
The agency's Otago-Southland highway manager, Ian Duncan, said in addition to the planned curve warning signs and barriers, the agency would also review the route to see if additional work was needed to manage the head-on crash risk.
''Even with the safety improvements we have carried out, the Kawarau Gorge is still a challenging stretch of highway that requires motorists to drive to the conditions,'' he said.
On average, 3200 vehicles a day use the highway.
Mr Duncan said the most common cause of crashes in the gorge (55%), was loss of control on a bend, resulting in either crossing the centre line and running off the road or having a head-on crash.
''These crashes are where the driver makes an error such as entering a bend too quickly for the conditions.''
The next highest crash cause at 22% is loss of control on a straight section.
''In these crashes, the driver inadvertently crosses the centre line and either hits another vehicle or runs off the opposite side of the road.''
From 2006, the Kiwi Road Assessment Programme crash risk rating for the gorge highway has improved from medium-high for both collective and personal risk to low-medium for collective risk and low for personal risk in 2012.
The programme uses crash data to show risk, plus other data, to give roads a star rating.
