Waterview Connection

Project Capabilities

Civil Mechanical Roads Tunnelling

McConnell Dowell, as a part of the Well Connected Alliance, designed, constructed and operated the Waterview Connection project, the largest road project ever undertaken in New Zealand. The 5 km, six lane motorway has 2.5 km of constructed underground as two 3-lane tunnels – a first for New Zealand. These twin tunnels are the largest diameter tunnels built in Australasia, and utilised ‘Alice’, the world’s 10th largest TBM with an excavation diameter of 14.46m, to break through. The five year design and construction phase is followed by a 10 year operation and maintenance alliance agreement, with NZ Transport Agency assuming full operation in 2026.

FAST FACTS

  • 550,000 m3 bulk excavation
  • 800,000 m3 tunnel spoil
  • 25,000 m2 bridges
  • 22 km road barriers
  • 100,000 m3 (24,000 segments) tunnel lining concrete
  • 80,000 m3 structural concrete
  • 600 km cabling
  • 32 km pipework
  • 64 jet fans

PROJECT OVERVIEW

The construction of a major infrastructure project in an urbanised area is a challenging task which will result in some impacts on the surrounding environment. The Alliance is committed to mitigating the effects of motorway construction and facilitating improvements to the surrounding environment by

  • Constructing 2.5 km of motorway underground (more than half of the new section of motorway);
  • 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 works; and
  • Implementing stringent construction management practices to minimise effects on the local environment, traffic network and communities.

A 3,600 t, 14.5 m diameter Herrenknecht EPB TBM will bore twin tunnels at depths of between 10 m and 45 m – the largest diameter tunnel to be built in Australasia and 11th largest TBM constructed to date worldwide. The TBM arrived in segments and was assembled in the southern approach, 30 m below the surrounding ground. Boring commenced from the southern portal in the southbound tunnel and was driven northbound for 2.4 km. When the TBM reached the northern portal, it was turned around on a turntable platform, moved across to the north bound alignment and relaunched to complete the drive back to the southern portal. Tunnel spoil was transported by conveyor back down the south bound tunnel to a loading facility at the southern portal. This will involve a 180 degree u-turn of the conveyor at the northern portal.

The successful award of this contract following a protracted competitive alliance process can be attributed to good partner selection and interaction and the early resolution of options, which allowed us to develop an attractive, single option to a higher level than the competition. 

The Challenge

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 and had the potential to impact on the surrounding environment.  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 have been preserved throughout construction.

The Solution

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 is almost 90 m and facilitates the installation of the tunnel lining which consists of 10 t two metre wide pre-cast concrete segments in rings of 10 and temporary electrical and mechanical services installation.

Key to Success

The Alliance has been committed to mitigating the effects of motorway construction and facilitating improvements to the surrounding environment by:

  • Constructing 2.5 km of motorway underground (more than half of the new section of motorway)
  • 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.

The successful award of this contract following a protracted competitive alliance process can be attributed to good partner selection and interaction, and the early resolution of options, which allowed us to develop an attractive, single option to a higher level than the competition.