Customer: New Zealand Transport Agency
Contract type: Alliance
Location: Auckland, New Zealand
McConnell Dowell, as a part of the Well-Connected Alliance (WCA), designed and constructed the Waterview Connection project, which included five kilometres of new motorway, including dual three-lane tunnels, each 2.4 km long and 13.1 metre internal diameter.
These twin tunnels are the largest diameter tunnels built in Australasia using the world’s 10th largest TBM. The five year design and construction phase is followed by a 10 year operation and maintenance phase. Since opening to the public in July 2017, it has dramatically improved traffic flows in and around the city.
The Waterview Connection is considered New Zealand’s most challenging infrastructure project to date.
The project was delivered in a constrained urban environment requiring extensive stakeholder and traffic management. North of the tunnel portal is the Great North Road Interchange, which comprises four ramp structures (similar in size to ‘Spaghetti Junction’) directing traffic into and out of the tunnel and connecting to SH16. This work required significant coordination with the existing motorway and Causeway contract being delivered by others. The ramps also traverse a Coastal Marine Area with various archaeological features that were preserved throughout construction.
The TBM commenced tunnelling in November 2013 after 21 months of preparation, involving the removal of 100,000 m3 of basalt and 200,000 m3 of sandstone at the southern portal. The length of the back-up gantries behind the 2,800 t TBM was almost 90 m and facilitated the installation of the tunnel lining which consisted of 10 tonne, 2 m wide pre-cast concrete segments in rings of 10 and temporary electrical and mechanical services installation.
McConnell Dowell is thrilled to have received recognition from the NZ Transport Agency for ‘Going the Extra Mile’ on the Waterview Connection. For the second year running, Waterview won the Connecting with Our Community Award, reflecting the project team’s commitment to engaging with the community beyond normal expectations. With the project area spanning five suburbs, the team has “walked with the community” in small and large ways including formation of a community design group, management of cultural impacts in partnership with key mana whenua partners, and co-designing a playground with the local school, a process which won the team the Best Practice Award from the NZ Planning Institute.
Key to Success
The WCA was committed to mitigating the effects of motorway construction and facilitating improvements to the surrounding environment by:
- Constructing 2.5 km of motorway underground
- Minimising the number of properties affected through the project design process
- Replacement of public open space impacted by the project along with amenity improvements, including planting and landscaping and restoration and rehabilitation work
- Implementing stringent construction management practices to minimise effects on the local environment, traffic network and communities.
Innovation in communication recognised diversity of people and communities and included multiple forums: a coffee bar and community garden; expertise within the community being harnessed; and different communities recognised by targeted project updates. This was in addition to regular Liaison Groups and meetings - unique to Waterview.