A board of inquiry has given the green light to the Waterview Connection, a stretch of road linking central Auckland to the airport.
The 4.5km link completes the Auckland Western Ring Route by connecting State Highway 20 to the North-Western Motorway (SH16).
In September 2010 the Government directed that the Waterview Connection Proposal be considered by an independent Board of Inquiry chaired by Environment Court Judge Laurie Newhook.
Traffic between Auckland and the airport is expected to reduce by more than a quarter once the Waterview Motorway offers faster trips.
Transport Minister Steven Joyce welcomed the approval of consents.
"We are today a big step closer to unlocking the benefits that the completed Western Ring Route will bring to Auckland and the whole country," he said.
"This is a project that's been debated for decades. The Government came in with a plan that was much less costly than the previous government's, while balancing the needs of communities along the route.
"The completion of the route is essential to the continued growth and economic development of the Auckland region.
It will also contribute to better business and freight links between key industrial hubs in Manukau, Auckland, Waitakere and North Shore," Mr Joyce said.
A 2005 report to the airport company highlighted a wide variation in trip times on the existing tortuous route, from 16.5 minutes to 47 minutes.
Trip times have become more reliable since a duplicate motorway crossing of Manukau Harbour opened last year, but visitors and commuters still face congestion once they reach local roads.
Construction is expected to begin before Christmas.
- Herald online staffBy Mathew Dearnaley Email Mathew