The Transport Agency has awarded a $1.4 billion contract to build the Waterview Connection project in Auckland.
The Well-Connected Consortium, led by Fletcher Construction, won the tender to construct 5km of motorway and road tunnels by 2016.
The road will connect the Southwestern Motorway at Mt Roskill with the Northwestern Motorway at Waterview.
Transport Minister Steven Joyce says the Waterview Connection will be the largest and the most expensive roading project built in New Zealand.
Construction is expected to begin in November.