Tonkin + Taylor’s Geotechnical Ingenuity on New Bridgewater Bridge Sets New Industry Precedents
We’re proud to be recognised with the 2025-2026 Consult Australia Award for Innovation for Excellence for our groundbreaking contribution to Tasmania’s New Bridgewater Bridge (NBB) project.
Project overview
The NBB is Tasmania’s largest-ever transport infrastructure undertaking, a new 1.28km, four-lane crossing of the River Derwent that replaces the 1946 steel-truss lift bridge. The new bridge includes a shared path for cyclists and pedestrians and delivers a safer, more reliable connection between Hobart’s northern suburbs and the Midland Highway.
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.”
Deep monopile foundation design
As lead geotechnical designer, Tonkin + Taylor delivered one of Australia’s most technically demanding foundation systems. The team pioneered the design of large-diameter monopiles reaching depths of up to 91.5 metres, believed to be the deepest of their kind in the Southern Hemisphere. These foundations were engineered to perform under highly variable ground conditions, seismic hazards such as liquefaction and lateral spreading, and significant flood-scour risk in the Derwent River.
Tonkin + Taylor’s design incorporated one-borehole-per-pile site investigations, 3D geological modelling using Leapfrog, and new classification methods for the Tertiary Sedimentary Breccia, alongside innovative analytical processes for assessing mixed soil-and-rock strength and stiffness. The firm also developed a new numerical simulation process to more realistically evaluate pile behaviour under multiple loading conditions.
Testing + verification
Another major breakthrough was the use of O-Cell load testing on four sacrificial piles to verify the design performance of large-diameter production piles. Therefore, confirmed pile capacities exceeding the minimum requirement prevented the need for pile redesign and lengthening during the construction phase, which could have led to a major project delay and budget blowout.
All 46 production piles achieved “Class 1” integrity in Cross-Hole Sonic Logging (CSL) testing, delivering a true “right-first-time” installation that prevented costly, time-consuming remedial work, safeguarded the construction program, and ensured total foundation reliability.
What this means for future river crossings
The project team set new industry benchmarks for geotechnical excellence. The team also established a new global benchmark for geotechnical engineering in complex riverine environments. Its comprehensive dataset now acts as a gold-standard benchmark for future projects in similar riverine conditions. This offers an invaluable reference for designers and asset owners worldwide.
“This achievement reflects what can be done when innovation, engineering excellence, and collaboration come together,” Tim Fisher, Tonkin + Taylor’s Group Managing Director, said. “The New Bridgewater Bridge shows that world-class engineering can deliver safer, greener, and smarter infrastructure.”
The project’s success leaves a lasting legacy as a demonstrated model for cost-effective, rapid, and resilient infrastructure delivery. The New Bridgewater Bridge represents Tasmania’s largest infrastructure investment and showcases Australian engineering excellence.
Read more about the New Bridgewater Bridge project here
Tonkin + Taylor’s pathway: Our purpose + vision
Pictured left to right: Katrina Dodd, McConnell Dowell | Tonkin + Taylor: Alex Ting, Dr Daiquan Yang, Tim Chadwick, Wendy Greatbatch, and Richard Hancy.
