The Prime Minister has turned the first sod on the Hamilton section of the Waikato Expressway.
The 102-kilometre expressway between Cambridge and Auckland is due to be fully completed by 2020.
The 22-kilometre Hamilton section will allow motorists to bypass the city and will link to the Ngaurawahia and Tamahere sections, which are already completed.
Work on the Hamilton section is due to start this month and is estimated to cost $973 million.