The NZ Transport Agency has announced a $5.4 million upgrade of State Highway 1 from Lookout Point, Dunedin, to Mosgiel.

Improvements include new safety barriers an "high performance" road markings to improve visibility at night and in wet conditions.

Two people died and 34 were seriously injured on this section of highway between 2006 and 2015, with nearly 90 per cent of serious crashes caused by vehicles running off the road and hitting a ditch or embankment.

Work will begin in July and should be completed by Christmas.