What began as a simple steel alternative to the many concrete tunnel lining segments at cross-passage locations evolved into a globally significant innovation in steel construction, supporting a lower-risk, high-productivity tunnel boring methodology.
Challenges of this scale don’t come easily. They require genuine collaboration from the design stage, with all stakeholders bringing their expertise to the table. Complex geometries, significant construction forces, thick steel plate, heavy welding, tight finished tolerances and an ambitious program – this project had them all.
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Bowhill brought together decades of steel fabrication experience with the T2DA team’s tunnelling and engineering brains-trust to develop something quite special. The design was optimised to withstand both the forces during tunnel construction and those it will carry permanently, while remaining as practical as possible to manufacture. Importantly, this included the use of large-scale robotic welding combined with precision machining after welding – bringing advanced manufacturing techniques to a scale rarely seen in Australian structural steelwork.
Example of Main Tunnels showing cross tunnel passages with openings.
Example of Tunnel Opening, made up of 6x & a soft eye segments
Example of Segment – approx 10 tonne
With each completed steel segment weighing just over 10 tonnes on average, the scale of the package is significant. At around 7,000 tonnes of fabricated steel in total, it is roughly equivalent to the weight of the iron structure of the Eiffel Tower in Paris.
It’s a project that demonstrates what can be achieved when design, engineering and manufacturing come together from the beginning.
