26 September 2013 - As a tunnelling design, procurement and construction specialist, Tom is recognised as a leading international technical advisor for major tunnel-based projects.  

He has over 20 years’ of practical experience, including the design of underground railway tunnels in Australia, UK and Hong Kong, and has overseen the successful design and construction management of 6km of complex wastewater tunnels in Auckland.  

We caught up with Tom recently to talk about his recent role as the Technical Advisor on the Waterview Connection tunnelling project being constructed in Auckland, New Zealand.

What is the Waterview Connection tunnelling project?

This is a great project. Owned by the NZ Transport Agency, the project is to build a 6.5km, six lane motorway connection between Auckland’s Southwestern Motorway (State Highway 20) and Northwestern Motorway (State Highway 16), which when completed will be New Zealand’s longest and deepest road tunnels.

The Waterview Connection is the final link in the long-planned Western Ring Route, a 48km motorway route that bypasses central Auckland. It will therefore end Auckland’s reliance on a single motorway spine – SH1 and the harbour bridge – for road travel through the region.

The NZD 1.4b project involves:

• Designing, building and commissioning two 2.4km long, 13.1m diameter bored tunnels up to 45m beneath Avondale and Waterview.
• Connecting the tunnels to the existing motorway network – SH20 at the southern (Owairaka) end and SH16 at the northern (Waterview) end.
• Expanding the Great North Road motorway interchange to provide connections between the tunnels and SH16.

It’s actually one of New Zealand’s largest roading projects since the Auckland Harbour Bridge was built in the 1950s, and is being delivered by the Well-Connected Alliance.

As NZTA’s Owner Verifier on this project, what are some of the key aspects of your role? 

As part of NZTA’s assurance on the project, my role is to review all the design submissions, to confirm compliance with the project requirements, and to focus on whole of life considerations, maintenance provisions and risk management. I am also part of the Value for Money team which has saved over NZD 30M on the project so far, by challenging the design and coming up with more cost effective solutions.

I also have a site surveillance role and have been reviewing the construction method statements, whilst also having an inspector based out at the brand new Precast Segment manufacturing facility helping to achieve the quality required for the tunnel lining segments. 

A special Tunnel Boring Machine (TBM) has been brought in from China.   Is this a new type of technology/machinery that is being used globally and/or in New Zealand?

Yes, the TMB (nicknamed “Alice”) has been supplied by the manufacturers, Herrenknecht, located in Germany and manufactured at their facility in China.   Designed and built specifically for this project, and with a cutting head measuring over 14m (as large as a four-storey building), it is the 10^th largest ever used in the world (the largest being 17 526m). I was involved in supervising the first Earth Pressure Balance TBM in New Zealand on Project Hobson, but the scale of this machine presents whole new challenges.

The mega-machine will take two years to complete its underground journey from Owairaka to Waterview and back. It will place 24 040 tunnel lining segments as it goes and will excavate 800 000 cubic metres of spoil.

It will take 2 404 rings to line the Waterview tunnels. Each will be two metres wide and will comprise 10 segments, all of which will be precisely manufactured at a state-of-the-art precast facility at East Tamaki with the capacity to store up to 8 000 segments.

Some key facts about Alice:

• The machine cost NZD 55 million dollars to build and transport to New Zealand
• It requires 16 people to operate the machine at any one time
• It is as heavy as 750 elephants weighing in at 3 000 tonnes
• The machine is made from a number of materials but the main components are:
  • The structure is made from a special sort of steel that has been made to handle extreme pressure
  • The wiring and motor cables are all made of copper and weigh 10 tonnes alone
  • Gold wiring on the computer systems and programmable controllers
  • Conveyor belts are made from layered rubber with steel wire reinforcing for strength
• The top speed for the machine is 8cm per minute, the top speed of a snail
• To prevent the cutting face getting stuck, foam is injected into the soil through pipes in the cutting head, along with water, to help turn the soil into paste which can then be more easily removed.

As a tunnelling engineer, what has been the most exciting aspect of this project and what will be the key milestones?

This project is world class.  My team prepared the detailed specification for the TBM used for the procurement and it has been exciting to see the detailed design of the machine develop. We also took part in the Factory Acceptance Testing in Nansha, China back in March this year.  Alice has now been shipped to New Zealand and is being assembled ready to commence tunnelling by the end of October.  

Having spent over three years working on the project it will be very satisfying to see tunnelling commence – but that is when the real excitement starts!  

We will monitor the progress over the next two years for NZTA, with tunnelling scheduled for completion in September 2015.

NB:  Alice is open to the public to view in Auckland on 13 October 2013.