Tunnel boring machine Kathleen is progressing well, digging the first tunnel of the historic metro rail crossing deep under Sydney Harbour. It has completed more than 550 metres of tunnel.
The TBM is currently in soft sediment about 40m under the harbour surface, progressing to hard rock conditions.
The under-harbour tunnelling machine uses compressed air to operate in soft material found in this section of the harbour.
The machine uses state-of-the-art tunnelling technology to safely make its way under the harbour through the expected conditions of clay, silt and sediment.
There may be some visible water activity on the surface, intermittently, during this part of the tunnelling process as the machine heads to harder materials.
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 after that, the whole TBM will be retrieved at Blues Point and taken away by barge.