The NZ Transport Agency’s Waterview Connection team in Auckland is celebrating a key project milestone with the successful lowering into place of the 350 tonne main drive that will power the project’s giant tunnel boring machine (TBM).
The main drive, the critical component that will enable the cutting face of the TBM – known as Alice – to rotate and bore the twin tunnels that will connect the Northwestern and Southwestern motorways, was lowered 40 metres into the deep trench where the machine is being reassembled.
The Transport Agency’s highways manager, Tommy Parker, says the operation demonstrated both the complexity and preparation required for the country’s biggest ever roading project.
“This single operation illustrates that this is a project of unprecedented scale in New Zealand,” says Parker. “To have completed it with such little fuss, as if an everyday task, should give all the project’s stakeholders – which in this case is the whole of New Zealand – great confidence in our team’s ability to meet the many challenges that lie ahead in its safe delivery.”
The manoeuvre was carried out using a 600-tonne crane, and required the construction of a deep-piled, reinforced crane platform, capable of supporting a total weight of almost 1200 tonnes above the trench. Despite being only a temporary structure, the platform required deeper and longer piles than any of the permanent structures on the entire project.
Three weeks after arriving in her many pieces, Alice is beginning to take shape in the excavated trench of the future tunnels’ southern approach. Reassembly involves the painstaking reattachment of over 300,000 bolts, ranging in weight from a single gram to 4kg. 10,000 of these will be in the main shield alone.
The distinctive 14m-wide cutting face – which makes Alice the 10th largest machine of its kind in the world – is scheduled to be lowered into place towards the end of September.
The TBM is due to be commissioned and start tunneling in late October.
