Waterview Connection

NZ Transport Agency's NZD1.4bn Waterview Connection is New Zealand's largest, most ambitious roading project to date and has had the biggest impact on how people travel in Auckland since the opening of Auckland Harbour Bridge in 1959.

First anticipated in transport plans for the city in 1954, Waterview took approximately 60 years to come to fruition due to geotechnical and community approval constraints.

The project includes twin three-lane tunnels at 13.1 m diameter x 2.4 km long – the longest road tunnels constructed in New Zealand, including a motorway-to-motorway interchange.

Waterview Connection was delivered by the Well-Connected Alliance (Alliance), responsible for the design, construction, initial maintenance and operation of the project.

Opened in 2017, Waterview Connection was the final five km- link completing the Western Ring Route (WRR), a second 47 km motorway which eased congestion on the main corridor through central Auckland and was identified by the NZ Government as one of its Roads of National Significance to support the country's economic growth. Bypassing the city centre to the west, the WRR links Auckland’s Manukau, Waitakere and North Shore regional centres improving regional connections north and south of the city.

Alice, the 10^th  largest earth pressure balance tunnel boring machine (TBM) in the world, was used to build the project's tunnels. It measured 87 m in total and weighed 2400 tonnes (3100 tonnes when combined with backup gantries), featuring a 14.4 m diameter rotating cutting head attached to the front of a 12m-long shield. Alice was followed by three gantries housing all the equipment required to place precast concrete segments to line the tunnels and remove all spoil.

Most of the tunnel route passes through sandstone featuring unique ground sediment, challenging seismic conditions and high water inflows. The size of the TBM was chosen because it could provide the best capability to handle the varying soil and rock conditions in its path, managing the project's geotechnical risks while minimising cost and programme risks.

The Alliance worked collaboratively with KiwiRail and Auckland Transport to manage risks involved with the shallow tunnel crossing under the live North Auckland rail line, roads and critical utilities. Developing real-time continuous survey monitoring and communications protocols helped minimise risks to workers and the public, ensuring the precise location and performance of the TBM were safely managed.

The tight construction site beneath the existing motorway required an innovative construction method using a purpose-built self-launching gantry. The 98 m-, 140 tonne gantry was used to construct four interchange ramps over the operational SH16 and New Zealand’s busiest arterial, Great North Road. It is a unique piece of equipment, designed specifically to fit the physical constraints of the design and the parameters of the beams, achieving significant time savings for the works.

The consents process developed between the project team, Auckland Council and the Ministry of Business helped to fast-track the 140 building consents required for the project. The Alliance, together with Auckland Council spent 12 months developing and formalising a charter that set out an agreed process, saving significant time and costs in approvals and consultations. It was recognised as a successful regulatory delivery model for public and private infrastructure by Auckland Council.

During the bid phase, the Alliance identified two significant areas of risk: the design and production of the 24,000 pre-cast tunnel lining segments, and the design, procurement, installation and commissioning of the tunnels mechanical, electrical and fire protections systems.

These two packages of work represented approximately 20per cent of the total contract value. In light of this, a decision was taken to manage risks using an innovative sub-alliance contract arrangement whereby two specialist subcontractors (Wilson Tunnelling for pre-cast and SICE for M&E) were partnered with under collaborative risk-sharing sub-alliance contracts.

This arrangement allowed the expertise of the specialist subcontractors to be fully utilised, while ensuring that the delivery of the sub-alliance scopes were fully integrated with overall project delivery. This meant that all parties were engaged in ensuring the best interests of both the Alliance and sub-alliances were addressed.

A project the size of Waterview inevitably garners attention in the local community. In order to manage community concerns raise, the Alliance undertook an annual Community Survey and created interactive community groups including the “Community Design Group”, the “Skatepark and BMX Working Groups” and the “Playground Working Group” (which included local children) to facilitate the input of community stakeholders into project design decisions.

The NZ Planning Institute recognised the Alliance for this commitment to community, awarding it the Best Practice Award (Consultation and Participation Strategies and Processes).