In the construction industry, there is historically a wide division between the design and construction aspects of a project. By bringing together these two aspects, there is often the opportunity for designer and the construction team to work together in a flexible and innovative manner to produce a better product. The result is the design and build concept.

The central factor that differentiates a traditional construction contract is the tranfer of the design obligation from an independent consultant to contractor. This tranfer has wide-ranging implications. Design and build projects require a re-examination of the allocation of risks and responsibilities, and it is important for the owner to ensure that the contractual framework gives practical effect to that allocation.

The extension of State Highway 20 at Mangere Aucland, is an 24 million AUD project involving the construction of 4.5 km of motorway, including six vehicle bridges and three pedestrian bridges. It is the largest design and build roading contract to be undertaken by the controlling authority, Transit New Zealand.