Work finally starts on NZ's 'most complex' road project

Auckland's Waterview Connection will require underground work at an 'unprecedented scale'. Photo / supplied

Work has finally begun on the $1.4 billion Waterview Connection in Auckland, with the first sod turned over.

Officials gathered at the site in Owairaka this morning where excavation will begin on a 30m-deep trench.

It is the first step for the construction of the twin 2.4km tunnels beneath suburban Auckland, which is on track to begin next year.

Excavating the trench will involve a series of explosions to fragment hard rock and the basalt retrieved will be used throughout the project for landscaping.

An 85m-long tunnel boring machine will be assembled in the trench.

New Zealand Transport Authority state highways manager Tommy Parker said a lot of work had been done, including relocating wildlife and plants life, in preparation of starting construction.

He said the tunnel boring machine would descend 45m beneath the surface, passing below hard volcanic rock and leaving intact the open space, communities and commercial precincts above.

"To create the launch pad for the machine we first have to excavate through a significant chunk of this basalt to reach the softer soil conditions below and that is the process we have officially begun today,'' Mr Parker said.

Prime Minister John Key, who joined the sod-turning, said the Waterview Connection was the country's "biggest and most complex'' road project and one of the Government's seven roads of national significance.

Mr Key said the motorway link - saving 15 minutes on the journey between the CBD and the international airport - would have "knock-on'' benefits for commuters, businesses, tourists and commercial transport operators.

"One of the National-led Government priorities for this term is to continue building a more competitive and productive economy and this project will help deliver on it.''