In January 2023, New Zealand’s Coromandel region was hit by severe weather causing a 115m long and 20m deep underslip on SH25A. We worked on a solution with NZTA and partners, enabling the highway to open six months after design commenced.

In January 2023 New Zealand’s Coromandel Peninsula experienced a 1-in-200-year storm. 300mm of rain fell in 60 hours, causing a large underslip on State Highway 25A (SH25A).

Reopening the road required a three-span bridge to be designed and built. Beca (Bridge Engineer), Tonkin+Taylor (Geotechnical) and McConnell Dowell and Fulton Hogan (Constructor in a joint venture) formed a team that drove an unprecedented level of collaboration with NZTA Waka Kotahi, local supply chain and community.

A project this scale usually takes up to two years, particularly given the challenging physical location, variable geotechnical conditions and limited contractor capacity.

Clear and delivery-focused client objectives enabled creative and efficient decision making, further reducing delays. The use of off-site construction, utilising available materials, executing design and construction in parallel, and incorporating innovations developed for other similar projects kept the project on track.

The team delivered a new 100-year design-life bridge in six months, representing an industry step-change in collaboration and project delivery. The accelerated design and build programme finished three months early, under budget, and just in time for Coromandel businesses to welcome visitors for the holiday season.


Bridge across the slip

6 months

Delivery timeframe

3 months

Ahead of schedule

SH25A - aerial view of slip and bridge mid-construction in Mid-November2023
SH25A - aerial view of the completed bridge in mid-December 2023.
SH25A - aerial view of slip and bridge mid-construction in Mid-November2023

Our People

Liam Edwards

Senior Associate - Bridge Engineering

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Nathan McKenzie

Principal / Technical Director - Geotechnical

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Tim Haig

Technical Director - Civil Engineering

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