One of the country's most important new roads has been given the go ahead and is likely to be finished within five years.
The Waterview Connection in Auckland is part of the $2 billion Western Ring Route around the city. In 2009 the Government classified the Western Ring Route as one of seven roads of national significance.
The NZ Transport Agency (NZTA) would not break down the cost of the Waterview Connection, saying it would "fall within the allocated $2bn in funding" for the Western Ring Route but on one of its web pages, said it would cost more than $100 million.
The Waterview connection includes two three-lane tunnels, widening and raising the causeway and other capacity improvement works from St Lukes to Westgate on the Northwestern Motorway (State Highway 16).
When completed the entire Western Ring Route would be a 48km alternative route around Auckland, reducing the dependency on State Highway 1 through the city centre and over the harbour bridge.
NZTA said the Western Ring Route was a key route which would help economic growth both regionally and nationally.
It said the seven "roads of national significance" were critical future roads to ensure transport users had access to significant markets and areas of employment and economic growth
NZTA state highways manager for Auckland and Northland Tommy Parker said the draft decision by the Environmental Protection Agency's Board of Inquiry to approve the Waterview Connection was an exciting and important milestone toward completing the Western Ring Route and unlocking Auckland's potential for economic growth.
"This is great news for both Auckland and New Zealand.
"This will be the country's largest and most complex roading project to date, and it will deliver significant benefits to New Zealand."
He said the completed Western Ring Route would create a transport solution for Auckland that would improve the state highway network and boost New Zealand's national economy.
The NZTA now had 20 days to review the draft decision from the board before the board released its final decision next month.
Tenders were likely to be awarded in August and construction would start soon after, said Mr Parker.