1. How much did the Tunnel cost to build?
$1.4 billion for the Waterview Connection project, including the Great North Road interchange.
2. How long did the build take?
Five years. Construction began in 2012 and the finishing touches, including signage and commissioning of the equipment was completed in June 2017. The project has been a long time in the making, with planning for providing the city with an alternative route beginning in the 1950s.
3. How many people worked on constructing the Waterview Tunnel?
The project employed around 11,000 people during a five year period and over three different work sites. The sites included the motorway and tunnel, a purpose-built pre-cast factory in East Tamaki and a disused Wiri Quarry.
4. How was the Tunnel built?
The tunnels were built by the 10th largest diameter (14.4m) tunnel boring machine (TBM) in the world.
A TBM is a large multi-functional piece of equipment which cuts through soil and rock with a rotating head, installing the concrete segments that line the Tunnel walls as it crawls underground at a top speed of 8cm a minute per hour – that’s the top speed of a snail.
The TBM, named Alice, worked around the clock, only stopping for scheduled maintenance and required shut-down breaks. Alice took about 1 hour 45 minutes to excavate 2 metres, stopped, and then took another 1 hour 45 minutes to install a set of 10 concrete rings 2 metres wide that lined the Tunnel. Alice then used that set of rings to push herself forward again and excavate another 2 metres.
At the same time the two large tunnels for vehicles were being constructed, a service culvert was built underneath to carry all the cables for the ventilation, lighting, communications and other services.
5. How was Alice named?
By tradition, a TBM is named after a woman and Waterview’s was called Alice. This name was put forward by a school boy in south Auckland who was inspired by Alice in Wonderland’s ‘tunnel’ adventures.
6. Where is Alice now?
After her final tunnel breakthrough in October 2015, work began immediately to dismantle the TBM. By March 2016 the TBM had been removed in parts from site. Some key parts of the machine were returned to its German manufacturer.
7. Could Alice be used for other projects?
The tunnel boring machine was designed specifically for the size and geotechnical conditions of the Waterview Tunnel and wasn’t suitable for other projects in New Zealand.
8. Where did the soil from inside the tunnels go?
About 800,000m3 of soil (enough to fill 320 Olympic-sized swimming pools) was excavated from the tunnels by Alice the Tunnel Boring Machine. As it was dug away, the soil (or spoil) made its way via a long conveyor belt to the on-site storage facility. From there the spoil was trucked to and filled the disused Wiri Quarry. In the future the old quarry site will be used for industrial development.
9. What if there’s a fire in the Tunnel?
The Tunnel is able to self-regulate in the event of a fire. If the thermal sensors detect a high level of heat the sprinklers will be activated. The sprinkler system for the Tunnel contains 5 deluge storage tanks each containing 250m3 of water for fire control and the drainage system will quickly channel the water away.
10. What does it look like inside the Tunnel?
The roof of the Tunnel is painted black and the walls are soft white. This colour scheme is a safety feature designed to keep distractions to a minimum and help drivers concentrate on the road.
11. Will mobile phones work inside the Tunnel?
Yes, the same system that enables car radios to work inside the tunnels will allow mobile phones to work. Only use your mobile phone in an emergency to keep distractions to a minimum.
12. When will the Tunnel close for maintenance?
We expect the tunnel will be closed for two to three nights a month for maintenance. The planned maintenance closures will only happen at night, when traffic is lightest and detour routes are in place.
13. What vehicles are not permitted to use the Tunnel?
Any Dangerous Goods Vehicles (those requiring a placard), vehicles over 4.3m high and any vehicle carrying an uncovered loose or bulk load are not allowed to use the Tunnel. These vehicles will be required to use the sign-posted detour route.
14. What is the speed limit inside the Tunnel?
Under usual circumstances the speed limit is 80km/h, ensuring safer journeys for everyone. The maximum speed limit can be changed for safety reasons by the overhead signs.
Speeds will be enforced by Police and part of the enforcement measures include speed cameras to encourage safe and appropriate speeds in and around the Tunnel.
15. What is the height restriction of the Tunnel?
The maximum vehicle height allowed inside the Tunnel is 4.3m. Any vehicle of or above that height cannot use the Tunnel and will need to follow detour routes.
16. Why is there no access to join the tunnel from Pt Chevalier or Waterview?
Various local connections were considered during the planning and consultation phases of the Waterview Connection to provide improved access between SH20 and suburbs such as Waterview, Avondale and Rosebank Peninsula. However these connections would have resulted in large increases in traffic on local streets, and may have required properties to be removed to make space for on and off ramps.
Local access was a particular issue for the Waterview and Pt Chevalier communities during the planning hearings for the project. Many reasons for and against the additional ramps were put forward.
The Board of Inquiry concluded that it was not practical to build more ramps at the Great North Road interchange because of space constraints. Also, there could be unacceptable environmental impacts for the Waterview and Pt Chevalier communities, including additional house removals.
Residents in areas surrounding the Tunnel are still able to use the local road network to access SH16 and SH20. The opening of the Tunnel has meant less traffic on the local road network as drivers choose to use the Tunnel to access the State Highways.
17. How is traffic managed around the Tunnel?
There are a number of traffic management tools available to respond to safety and heavy traffic conditions in and around the Waterview Tunnel. Traffic management tools include:
On-ramp signals – are on three of the four ramps at the Great North Road Interchange, in addition to existing ramp signals at other ramps along the Northwestern (SH16) and Southwestern Motorways (SH20). Two of the Waterview ramp signals can be used to control traffic entering the southbound tunnel from either direction on the Northwestern Motorway. The third can be used to control traffic leaving the Tunnel and joining Northwestern Motorway lanes heading towards the city centre. The ramp signals are not used all the time. The Waterview ramps signals can manage very heavy traffic when necessary for safety and efficiency.
Barrier Gate System – can be used to physically stop vehicles entering the Tunnel. Barrier gates are at the entrances to the Tunnel and on the Maioro Street northbound on-ramp.
Over-Height Vehicle Detection System – detectors and Variable Message Signs are ahead of all entries to the Waterview Tunnel. When the detectors are triggered the signs are activated and an alarm is generated.
Dynamic Lane Control Signs - react to current traffic conditions and can close/open lanes as necessary. The changeable message signs inform drivers of planned detours or lane closures/openings and are located just before the Tunnel entrance to inform drivers of the lanes they can use inside the Tunnel.
Variable Speed Limit Signs – inform drivers of legal speed on a particular section of motorway at that time.
Variable Message Signs –provide information for drivers including incidents, closures, journey times, speeds and lane closure.
18. How is traffic managed inside the Tunnel?
A number of traffic management tools are available to respond to safety and heavy traffic conditions either in the Waterview Tunnel or on the approaches:
Closed Circuit TV cameras – located every 60 metres.
Automatic Video Incident Cameras – detect unusual traffic behaviour such as vehicles driving the wrong way.
Variable Message Signs – to keep drivers informed of traffic conditions including incidents, closures, speeds and journey times.
Variable Speed Limit Signs – allow speed limits to be adjusted to suit Tunnel conditions.
Lane Control Signs – advise drivers if a lane is open or closed.
Incident Response Crew – a 24/7 incident response crew will be based at the northern end of the Tunnel. During peak hours the crew will be split so there is coverage at either end of the Tunnel.
Other tools – in addition to traffic management tools inside the Tunnel there is also 24/7 monitoring by operators, a public address system, full mobile and radio rebroadcast coverage, emergency telephones every 150 metres, ventilation fans to remove fumes, sprinkler/deluge system to control fire or spills, and 18 emergency exits located every 150 metres to allow people to cross from one tunnel to the other. These exits are only to be used if there is an incident or emergency.
19. Why are there on-ramp signals?
On-ramp signals are just one tool to optimise traffic flow and ensure the safe and smooth running of the entire Auckland motorway network. Ramp signals, similar to those operating where SH20 joins SH1, will help to manage traffic flow on both ramps leading in to the Waterview Tunnel and the city-bound ramp out of the Tunnel.
20. Was anything found during excavation of the tunnels?
Work began at the southern end of the project, in Owairaka, in January 2012. Although there are no known archaeological sites here, project archaeologists were on site to monitor all initial earthworks, the removal of vegetation, realignment of Oakley Creek and the construction of services and temporary features. No archaeological features or sites were found.
Work at the northern portal in Waterview began in January 2013. This work was near the known ‘Star Mills’ flour mill and tannery site at 15 Cowley Street and near the former mill workers’ houses north of Cowley Street.
Project archaeologists identified the old mill race, an important find, as the exact location and the construction details of the mill race were previously unknown.
In the same area, two brick-lined drains, an old well and several bottle pits were identified. Some interesting 19th century artefacts recovered from the well and pits include an old school slate, ceramic pitcher, shoes, a lead bullet and decorated tobacco pipe. The location of the well and pits indicate they were associated with the mill workers’ cottages.
Excavations on the southern side of the mill race revealed the remains of a brick kiln structure. This is another interesting find as historical records refer to brickmaking by the original mill owner, John Thomas, who in 1864 had a contract to supply bricks for the construction of Whau Asylum (later Carrington Hospital). The location and type of kiln operated were unknown before being exposed during early works for construction of the northern tunnel approach trench.
21. When was the Tunnel opened?
A number of formal and community celebration events were held in between Sunday 18 and Tuesday 27 June 2017. The celebration events included opportunity for the public to walk and cycle through the Tunnel before opening to traffic in the early hours of Sunday 2 July 2017.