New Bridgewater Bridge – Tasmania

Project highlights

• Large-diameter monopiles up to 91.5 m depth (believed to be the deepest of their kind in the Southern Hemisphere).
• One-borehole-per-pile investigation approach.
• O-Cell load testing to verify test pile performance and to enhance programme certainty.
• All production piles achieved “Class 1” integrity.
• Design performance exceeded expectations.

• Highly variable ground conditions beneath a river environment
• Seismic hazards (including liquefaction-related ground deformation)
• Flood scour risk (riverbed erosion during major flows)
• A need to confirm performance early to avoid redesign, delays and cost escalation during construction

What we did

Tonkin + Taylor served as the lead geotechnical designer, working alongside the wider project team to design and validate a technically demanding bridge foundation solution. We combined detailed site investigations, advanced ground modelling, innovative interpretation methods, and verification testing to support a “right-first-time” installation approach, reducing rework risk and enhancing programme delivery.

Deep monopile foundation design

We pioneered the design of large-diameter monopiles reaching depths of up to 91.5 metres, engineered for performance under variable soil and rock profiles, earthquake loading and associated potential ground deformation, and scour and river-driven loading conditions.

Targeted investigation – one borehole per pile: To reduce uncertainty and strengthen design confidence, our approach included one-borehole-per-pile site investigations – providing high-resolution ground information for each foundation location.

3D geological modelling to manage complexity: 3D geological models enabled a clearer understanding of subsurface variability and helped the team align design decisions with real ground conditions.

Novel ground classification and advanced interpretation: Novel classification methods for the Tertiary Sedimentary Breccia were developed, which applied innovative analytical processes to better assess mixed soil-and-rock strength and stiffness – critical for predicting pile behaviour and designing efficiently.

More realistic numerical simulation of pile behaviour: Novel numerical simulation processes were developed to evaluate pile behaviour under multiple loading conditions, improving realism and supporting confident decisions in a complex foundation environment.

Verification testing that enhanced time + cost

Outcomes + benefits

• Reduced uncertainty through targeted investigations and 3D ground modelling.
• Verified foundation performance through O-Cell testing, supporting programme and budget certainty.
• High-quality construction outcomes, with all production piles achieving Class 1 integrity.
• A solution designed for seismic resilience and scour-related risk in the River Derwent.
• A comprehensive dataset that provides a valuable reference for future projects in similar river conditions.

Setting new benchmarks for geotechnical engineering

The New Bridgewater Bridge has set new benchmarks for geotechnical design and verification in complex geological conditions and river environments. The depth of the monopiles, the investigation strategy, and the testing-led validation approach have helped establish a stronger evidence base for bridge foundation design, supporting designers and asset owners on future projects worldwide.

Led by Dr Daiquan Yang – Senior Principal, Technical Director, and Project Director – the team worked closely with project partners to develop innovative approaches to overcome the complex geotechnical, scouring and seismic challenges of the site.

Daiquan shared: “It’s been a privilege to contribute to such a transformative project. The geotechnical complexity of the site demanded innovative thinking, expertise, and close collaboration. Seeing the New Bridgewater Bridge being recognised at the highest level is a proud moment for me and everyone involved.”

Innovation for Excellence Award: What this recognition means

Tonkin + Taylor’s contribution to the project was recognised with the 2025–2026 Consult Australia Award for Excellence | Innovation for Excellence, reflecting the value of combining innovation, engineering rigour, and collaborative delivery to achieve better outcomes.

“This achievement reflects what can be done when innovation, engineering excellence, and collaboration come together. The New Bridgewater Bridge shows that world-class engineering can deliver safer, greener, and smarter infrastructure.” Tim Fisher, Group Managing Director, Tonkin + Taylor, said.

The project’s success establishes a lasting legacy, a proven model for delivering infrastructure that is cheaper, faster, more resilient and more reliable. The New Bridgewater Bridge stands as both Tasmania’s largest infrastructure investment and a landmark of Australian engineering excellence.

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