A 16km expressway north of Wellington has had resource consent granted by a Board of Inquiry.
New Zealand Transport Agency (NZTA) had proposed the expressway be built between Peka Peka and north Otaki.
The road was part of the Wellington Northern Corridor, a development considered to be of national significance, so was referred to the board by Environment Minister Amy Adams last April.
The decision followed the Board's consideration of the application, submissions, evidence and a two week hearing.
Its decision could be appealed to the High Court on points of law only, and it could not be overturned by ministers.
NZTA's state highway manager Rod James earlier said the road was expected to be open by mid- to late-2017.
The expressway would not only provide an improved highway route through the Kapiti district but would also increase safety, reduce travel times and improve journey time reliability between the Kapiti Coast and Wellington, he said.
Six other roads of national significance (from north to south):
• Puhoi to Wellsford;
• Waterview Connection (Auckland);
• Victoria Park Tunnel (Auckland);
• Waikato Expressway;
• Tauranga Eastern Link; and
• Christchurch motorways.