The Supreme Court has dismissed an appeal from a group on the Kapiti Coast opposed to the building of the MacKays to Peka Peka Expressway.
A board of inquiry approved the $630 million project in April this year and an appeal to the High Court from protest group Save Kapiti was dismissed in August.
Save Kapiti then sought leave to appeal that decision to grant resource consent, but that challenge has on Thursday been declined.
Transport Minister Gerry Brownlee welcomed the Supreme Court decision, saying construction is set to begin within weeks on the long-awaited State Highway 1 expressway.
Mr Brownlee says it is a critical component of the Wellington Northern Corridor.
