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Customer: Whangarei District Council Location: Whangarei Contract type: ECI Construction Period: July 2013
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This ECI contract was for a new 265 m long bascule bridge crossing the Hatea River in Whangarei. The client, Whangarei District Council, had a bold vision for the bridge, seeking a structure that reflected the unique cultural heritage of the region.
Working closely with UK-based architect Knight Architects we produced a design modelled on the traditional Maori fish hook – hei matau – representing strength, good luck and safe passage over water.
The bridges form reflects its function as the “hook” (J-beams) is cantilevered and rolls back to raise the bridge deck, allowing for the passage of marine traffic.
The Challenge
Architecturally designed bridges like the Lower Hatea River Crossing are rare and achieve the clean, sharp lines that were a key feature of Knight Architects’ design required precision in construction.
Bascule bridges themselves are relatively common worldwide, but the type of bascule constructed at Lower Hatea is rare. Lower Hatea is a single leaf counterweighted rolling bascule, meaning that it is opened hydraulically using rams, from one side in the centre of the bridge, and makes use of counterweights which work with gravity to reduce the energy needed to raise the deck. As one of only a handful of bridges of this type in the world – and certainly none with such a distinctive design - there was really no precedent for how to manage the construction of the bascule section to ensure it could open smoothly, safely and in a reasonable timeframe.
Accommodating the client’s requirement that the navigational channel remain open during construction further increased the challenge.
The Solution
Around 3-4 months modeling and planning went into the development of the design for the bascule section, including determining the optimal number, configuration and location of the hydraulic rams needed to lift the bridge, and the amount of counterweight required in the J-beams.
The bridge now lifts by way of two 8 t hydraulic rams, some of the largest in the world. The bridge was built from both sides of the river separately, and the 390 t bascule section assembled on one side and then launched across the 25 m gap – an impressive engineering manoeuvre.
Keys to Success
Bringing together an international team of bridge experts, and working closely with the client throughout the project enabled us to work though the engineering challenges and ultimately, produce something great for the Whangarei community.
Awards
NEW ZEALAND
2015 IPWEA Public Works Medal for Public Works Project of the Year
2014 NZ Engineering Excellence Awards - Supreme Award Winner
2014 Civic Trust Awards - Winner
2014 CCNZ - Construction Excellence Award - Winner, Category 3 Projects with a value between $5 million and $30 million
2014 NZ Commercial Project Awards - Supreme Award Winner (Transfield Services & McConnell Dowell JV)
2014 NZ Commercial Project Awards - Gold Award Winner (Transfield Services & McConnell Dowell JV)
2013 NZ Concrete Society - Infrastructure Award Commendation (Transfield Services & McConnell Dowell JV)
2013 Roading Excellence Awards
- Z Energy Excellence Award for a Major Road Project
- Highly Commended in recognition of the planning design and construction (Transfield Services, McConnell Dowell, Whangarei District Council and Peters & Cheung
INTERNATIONAL
2014 Architizer A+ Award (Architecture+Engineering)
2014 United Kingdom Civic Trust Award
