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Mega borer Kathleen arrives to dig deep under Sydney Harbour

The tunnel boring machine (TBM), designed especially for the ground and rock conditions found at the bottom of Sydney Harbour, arrives at White Bay. Five TBMs will be used to deliver the tunnels between Chatswood and Sydenham for Sydney Metro City & Southwest.
The tunnel boring machine (TBM), designed especially for the ground and rock conditions found at the bottom of Sydney Harbour, arrives at White Bay. Five TBMs will be used to deliver the tunnels between Chatswood and Sydenham for Sydney Metro City & Southwest.

Sydney Metro’s fifth mega tunnel boring machine has arrived to begin the historic first rail crossing deep under Sydney Harbour.

Tunnel boring machine Kathleen is being assembled at the site of the new Barangaroo metro station, to start tunnelling under the Harbour in the coming months.

NSW Minister for Transport and Infrastructure Andrew Constance said this specialised TBM is named after Kathleen Butler, who played a vital role in the construction of the Sydney Harbour Bridge as the technical advisor to legendary engineer John JJC Bradfield.

“Not since Bradfield delivered the Sydney Harbour Bridge almost a century ago has there been a vision for public transport on the scale of Sydney Metro,” Mr Constance said.

“Now, TBM Kathleen is shaping Sydney’s future as she gets ready to build the first railway tunnels under Sydney Harbour – linking metro rail from the city’s northwest, through the CBD and on to the south west.”

Specially designed for the geological conditions under Sydney Harbour, the 975 tonne machine will dig twin metro rail tunnels from Barangaroo to Blues Point.

Kathleen arrived by ship at White Bay and was transported by barge to Barangaroo Station near Hickson Road.

Kathleen will start her journey deep underground later in 2019 from a massive cavern next to Barangaroo Station, which is being built to allow metro trains to cross from one rail line to another.

After building the first tunnel, TBM Kathleen will have her giant cutter head and main section lifted out at Blues Point and placed on a barge to return to Barangaroo.

The machine’s support trailers will be pulled back to Barangaroo inside the first tunnel.

Kathleen will then build the second tunnel under Sydney Harbour before being retrieved at Blues Point and taken away by barge.

The machine is expected to tunnel through clay, silt and sediment and will use state-of-the-art tunnelling technology to safely make its way under the harbour.

Each tunnel is about one kilometre long.

Traditionally tunnellers look to St Barbara for protection and tunnel boring machines are given female names.

In 1924, John Bradfield acknowledged the incredible work done by Kathleen Butler as his only assistant in preparing the specification for Sydney Harbour Bridge.

Ms Butler was the first woman in Australia to have such a senior role in managing a project of this scale.

TBM Kathleen will join the four borers currently digging from Marrickville and Chatswood towards the harbour’s edge.

Together all five TBMs will deliver twin 15.5 kilometre rail tunnels for Australia’s biggest public transport project.

Source: NSW Government

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