Auckland’s City Rail Link Ltd has advised the New Zealand Government that it will operate its 7.15m diameter Herrenknecht EPBM, boring the project’s 3.45km of twin tunnel, at reduced level allowed under current Covid-19 health and safety regulations.
“TBMs are not designed to be ‘parked’ underground for an open-ended period – they need to keep moving forward, even at reduced capacity, to avoid the risk of getting stuck,” says Dr Sean Sweeney, City Rail Link Ltd’s Chief Executive.
Dr Sweeney says the Ministry of Business, Innovation and Employment (MBIE) has been advised of the rationale for operating the TBM within current regulations.
“We are not planning to continue full-scale mining – the TBM will be working at a much lower level than full capacity. We will be operating on a ‘do minimum/as necessary’ basis that falls within the parameters of this month’s Covid-19 Public Health Response Order.
“This low-level operation will allow us to remove the risk of pressure from earth settling around a stationary TBM and ‘trapping’ the machine. If that happened here, the costs and time involved in freeing the TBM would be catastrophic and completely derail the project,” he says. Details of the low level operation are being finalised.
“Our priority will be to keep our workers safe – they will be working under strict health and safety guidelines. Our neighbour are being kept informed of our actions,” Dr Sweeney added.
The $4.4bn City Rail Link’s TBM, named in honour of Māori rights champion, Dame Whina Cooper, is a bespoke machine costing around $13M built specifically for Auckland’s soil conditions.
The TBM is operated by CRL’s main contractor, the Link Alliance comprising Vinci Construction Grands Projets S.A.S., Downer NZ Ltd, Soletanche Bachy International NZ Limited, WSP Opus (NZ) Limited, AECOM New Zealand Limited and Tonkin + Taylor Limited.
It began excavating the first of the project’s two rail tunnels in May – mining from Mt Eden first to Karangahape and then on to central Auckland to connect with already constructed tunnels from Auckland’s downtown.
A completed CRL and its two underground stations will give New Zealand’s largest city a world class railway – improved access in and out of central Auckland and quicker and more frequent trains across the wider city.