Western Ring Route

Western Ring Route, Auckland, New Zealand

The largest and most complex road infrastructure project in New Zealand

Auckland is New Zealand’s fastest growing and most populous city, projected to account for more than half of the country’s population growth by 2043. Critical to connecting the city and improving the lives of Aucklanders now and into the future, is the NZD $2.4 billion Western Ring Route (WRR) – the largest and most complex road infrastructure project ever undertaken in the country.

Since the opening of the 2.4 km underground Waterview Connection Tunnel in July 2017, the WRR’s 48 km network provides an alternative route around the city, allowing traffic to bypass the city’s central business district and State Highway (SH) 1. The WRR also establishes a new, direct link between the Auckland central business district (CBD) and Auckland Airport, and connects the city with Manukau in the South, West Auckland and the North Shore. In addition, the project offers increased capacity on existing motorway routes; substantial dedicated bus shoulder lanes; together with shared cycleways and pedestrian facilities to further facilitate alternative transport options to and from the city.

Today, the WRR and the Waterview Connection Tunnel offer Aucklanders shorter travel times and reliability, reduces congestion and improves the network’s resilience and safety. The project has unleashed the economic potential of New Zealand’s largest city and ensures the country is well positioned for future growth.

Projects of this size and complexity don’t just happen. It took over a decade of planning, trust and collaboration between Aurecon and its client, the New Zealand Transport Agency (NZTA), to deliver New Zealand’s largest ever road infrastructure project. Despite its complexity and a multitude of challenges never-before-seen in the country, Aurecon provided a full service, successfully working with the NZTA to deliver on the project objectives.

Earning client trust

Aurecon and NZTA’s journey began in 2005 when the company was commissioned to conduct the planning phases of the road design and widening works for the SH16 Waterview to Royal Road improvement project. In 2009, the relationship was extended to deliver the SH16 elements of the consenting design as part of the overall Waterview Connection, and the 2.4 km underground Waterview Tunnel. Drawing on international value engineering expertise in delivering similar projects, Aurecon identified over NZD $200 million of cost savings by reducing the tunnel diameter and augmenting the fire and life strategy to be fit for purpose.

Building momentum and trust with NZTA to find and solve project challenges, Aurecon was honoured to be appointed as the Principal Advisor for the remainder of the project in 2010 – overseeing owner verifier responsibilities of the Waterview Connection, along with the overall project management of the rest of the WRR suite of projects, which widened and improved the remainder of SH16 motorway between St Lukes Interchange through to Westgate.

As NZTA’s Principal Advisor, Aurecon assured NZTA of the necessity and technical quality of the work completed, as well as the management of the interfaces between the various projects, identifying and implementing various minor enabling projects. Aurecon also advised on procurement management, developing the concept of operations, and assisting with the operational integration of the new network.

It was a mammoth task, given the size and complexity of the project. Aurecon worked with the client every step of the way to manage risk, develop innovative solutions and, despite all odds, delivered the project to specification and on time.

Highlights of the client experience

Causeway value engineering

The height and breadth of the motorway section across the existing SH16 causeway needed to be increased for a 100-year lifespan to cater for the increase in traffic and projected rise in sea levels due to climate change. The task was challenging as the soft marine muds that support the causeway required stabilisation, and there was a need to keep the road fully operational during the work to minimise disruption to traffic.

Instead of increasing the breadth and height for 100 years in one operation, Aurecon advised the client to use a staged process of increasing the dimension over time to minimise the risk of settlement and slope failures. First, the height was increased to allow for a 50-year predicted sea-level rise – with the remaining work to be re-evaluated in the future as part of scheduled 40-year pavement rehabilitation works. The staged engineering solution improved constructability, reduced the project duration, and saved the client over NZD $50 million.

Regulatory approvals

The widening of the causeway had the potential to significantly impact the adjacent Department of Conservation (DOC) Marine Reserve designated for its importance to endangered habitat and bird species. Noise, sediment and stormwater runoff from the motorway had the potential to affect wildlife and reduce water quality, potentially harming the invertebrates that feed the birds.

Aurecon co-led the first board of inquiry (BOI) of its size to obtain the legal environmental approval for the project. The resilience and adaptability of the project to climate change were also key drivers for the BOI.

A BOI is a single regulatory process where a designating authority, like NZTA, can fast track legal environmental approval for a project of national significance by directly referring the matter to the Minister for the Environment. The success of the inquiry was essential to meet the time and budget constraints, placing significant pressure on the project team to provide a convincing evidence case.

Painstaking research in partnership with DOC, Forest and Bird New Zealand, coastal monitoring, noise monitoring, and advice from international colleagues (who are experts in environmental science, climate change and construction) convinced the government that the project was environmentally sustainable.

Procurement innovation

To achieve the minimum whole-of-life cost for the Waterview Connection, the team balanced capital cost associated with the design and construction, with the cost of operation and maintenance via a unique procurement innovation.

Aurecon worked with NZTA to introduce the first ‘design, construct and maintain’ procurement tender process, which competitively tensioned the best overall solution for the design and operation; important in view of the high ongoing operational costs associated with tunnels.

Operations planning and integration

Aurecon was engaged by NZTA to design the operations plan for integration and use of the WRR project into the existing highway network. Introducing such significant infrastructure that provides a new link on a major motorway is highly sensitive to opening operational issues.

Adopting intelligent transport systems software, the operations plan provided guidance to the client’s WRR control centre route-operators to manage and balance traffic flows, and make journey times shorter and more predictable. The opening was ultimately well managed with no significant operational issues.

Read more about the operations planning for the Western Ring Route.

Client feedback quotes about the project

“Aurecon has provided excellent service and performance on the Western Ring Route. The team challenged scope, standards and assumptions, finding more appropriate solutions to the project, which have resulted in some significant value engineering initiatives and providing a more affordable scheme. I was very impressed by the way the solutions were derived by the Aurecon team and articulated at our decision-making bodies for endorsement.”

‒ Sumi Eratne, Project Director, NZTA

“Aurecon provided excellent technical outputs, responsiveness and liaison throughout.”

‒ Kevin Stevens, Project Manager, NZTA