The NZ$655m (£325m) design-build contract involves the construction of a new 6.8km dual two-lane road together with cyclist and pedestrian paths. Eight bridges, 29 culverts and eight stream diversions will be built.
The project is designed to improve road safety and accessibility in the region, with a particular focus on protection of biodiversity.
Archaeological and environmental monitoring will be carried out during the preparatory works phase. Seven new wetlands will be created and endemic fauna - fish, insects, birds, lizards and bats - will be protected.
The works are scheduled to take around five years. At the peak of construction, up to 400 people will be employed on site.