Building the Waterview Connection in west Auckland involves a number of simultaneous construction projects, ranging from the diversion and upgrading of major services on the motorway route to construction of New Zealand’s longest road tunnels.
The overall project employs between 800 and 1000 people in a variety of roles. The project is spread over five separate sites including;
- a purpose built precast concrete manufacturing facility in East Tamaki
- a managed landfill at Wiri in South Auckland
- the motorway route between Ōwairaka and Waterview.
There are three main zones of construction:
- Southern: Above ground works from Maioro Road to the tunnels
- Tunnels: Underground works to build the twin tunnels
- Northern: Above ground works from the tunnels to State Highway 16, including the Great North Road interchange
Southern Construction Zone
The connection to SH20 includes work on:
- Widening the existing two-lane motorway to three lanes in the north-bound direction
- Expanding the Maioro Street interchange to include north and south-bound on and off ramps
- Linking Maioro Street to the tunnels
- Extending State Highway 20 from the Maioro Street interchange with three lanes in each direction
- A new road bridge to take Richardson Road over the motorway
- A 6-lane bridge to take the motorway over Oakley Creek
- A pedestrian/cycle bridge over the motorway between Hendon Park and Alan Wood Reserve
- A high-sided trench to take the motorway down to the tunnel portals - the Southern Approach Trench
- Realignment of Oakley Creek
- The relocation of Hendon sewer and major stormwater drainage systems away from the motorway route.
The Tunnels Construction Zone
Two tunnels, each to carry three lanes of traffic, are being built between Ōwairaka (the Alan Wood Reserve) and Waterview. Construction includes:
- Bored tunnels 2.4km long, 13.1m wide and up to 45m below the surface
- 16 cross passages connecting the tunnels, carrying services and providing a safe area for users in case of an emergency
- Ventilation systems connected to ventilation buildings at the tunnel exits and, in turn, connected to ventilation shafts or stacks
- A tunnel operations centre located within the southern ventilation building
- Monitoring, lighting, communication and fire suppression systems
- Utility service lines and tunnel drainage systems accommodated under the roadways
The Northern Construction Zone
The connection in the north, between the tunnels and Northwestern Motorway will include:
- A trench (called the Northern Approach Trench) to take traffic to and from the tunnel portals, which will be 26 metres below the surface.
- The Northern Approach Trench is being constructed as a cut and cover tunnel (a trench with a cover over it)
- A ventilation station at the exit to house tunnel services including the fans that draw in air from the tunnel and transfer it to a vent stack approximately 120m away
- The vent stack
- Four new ramps at the Great North Road motorway interchange to connect the tunnels and SH16.