Major works on the notorious section of highway known as the Akerama curves are expected to take two years to finish and to cost $13 million.
The more than two-year realignment job that started in March will see passing lanes put in, tight bends removed and inclines made less steep between Barnes and Rusk Rds on State Highway 1 near Hukerenui, 35 km north of Whangarei.
This and next year's programme will see most of the earthworks, drainage and stormwater systems finished, with final paving and landscaping in 2017.
The work includes creating a new wetland to offset the loss of one through the road construction and altered drainage.
Between 2004-2013 there were 64 crashes on that section of SH1, 53 of them from loss of control on bends, resulting in two fatalities and many injuries.