Thirsty work for TBM’s Betty and Dorothy
15 Jan 2024 |  

TBM Betty and TBM Dorothy – Australia’s first autonomous tunnel boring machines – are progressing well on their journey to carve out a section of the twin Sydney Metro West tunnels between Sydney Olympic Park and Westmead, having built 865 metres and 300 metres, respectively, of fully lined tunnels since launching from the Clyde launch box.

Dorothy, named in honour of human rights activist Dorothy Buckland Fuller AM, weighs 1,200 tonnes and is about 170 metres long – or longer than two Airbus A380s. Dorothy will cut through approximately 800,000 tonnes of shale and sandstone on her 4.5-kilometre journey towards Sydney Olympic Park.

For the first time in Sydney Metro history, TBM’s Betty and Dorothy will use non-potable water to excavate and cool themselves! TBM’s Betty and Dorothy will be guzzling more than 83,508KL of treated groundwater instead of drawing drinking water from the water network! This aligns with Sydney Metro’s commitment to reduce potable water use in construction by at least 10% (compared to business as usual) and will contribute to achieving a reduction in water from non-potable sources by a minimum of 33%.

The TBMs have artificial intelligence software developed by Gamuda installed inside the TBM, which has the capability to steer, operate and monitor the machine automatically. While an operator always remains in control of the TBM, the autonomous algorithm takes on the machine’s repetitive tasks, leading to increased speed and greater accuracy.

The progress of TBM Betty and TBM Dorothy reflects the milestones achieved by the Gamuda and Laing O’Rourke Consortium on behalf of our valued client Sydney Metro. A huge congratulations to our employees, partners and contractors involved in this project.

For more information about Sydney Metro West, visit