| 69 T T Karen Phelps Complex bridge build a showcase of skills The project was commissioned by Te Whakaari Incorporation, a Māori land trust, to replace a century-old suspension bridge. CIVIL Bridge It NZ Bridge It NZ was named a finalist in the 2025 Civil Contractors New Zealand Awards for its 50-metre truss bridge construction at Tukemokihi Station, a project that pushed the company’s engineering capabilities to unprecedented limits in some of New Zealand’s most challenging terrain. The project, nominated in Category 1 for projects under $2 million, represents what Kim Bevins, Bridge It NZ business manager, describes as the company’s most complex technical achievement to date. “This 50-metre truss bridge across Tukemokihi Stream in the rugged hills of northern Hawke’s Bay is one of Bridge It NZ’s proudest achievements. It is the largest single- span bridge we have ever built, in the most difficult terrain we have ever faced,” he says. The project was commissioned by Te Whakaari Incorporation, a Māori land trust, to replace a century-old suspension bridge destroyed when a macrocarpa tree toppled on to its support structure during a severe storm in mid-2022. Located on the 6200-hectare sheep and beef station, 35 kilometres from Wairoa, the site presented challenges that required innovative solutions. “Every conceivable challenge was thrown at us – from near impossible access, to battling harsh winter weather and having to design and execute a bridge launching methodology that we had never attempted before,” explains Kim. The remote location’s steep terrain, accessible only via hairpin bends and narrow, load-restricted bridges complicated by Cyclone Gabrielle damage, made conventional construction methods impossible. Traditional crane installation was out of the question, forcing the company to develop an entirely new approach. The solution involved manufacturing the bridge in five, modular 10-metre sections weighing five tonnes each, light enough for transport by tractor to the remote site. However, the most innovative aspect was the launch method – literally pulling the complete 50m bridge through mid-air from one riverbank to the other above a 16m drop. “A unique launch method had to be developed to literally pull the bridge 50 metres in mid-air from one side of the riverbank across to the other, something we had never done before,” says Kim. The engineering feat required constructing a 28m temporary launch frame, a 9m steel tower with forward and rear stays, and a sophisticated counterweight system using 23.5 tonnes of soil in bulk bags. A series of pulleys provided mechanical advantage, allowing a five-tonne tractor to haul the entire bridge across the ravine using 13mm dyneema rope. Project manager and engineer Craig Langsford planned 18 separate launch steps, with the centre of gravity precisely maintained throughout to prevent tipping. “The launch went exactly as planned, with the bridge sliding into place perfectly in a single day,” says Kim. The project’s complexity was compounded by delays in resource consent approval, pushing construction from the planned spring start into winter months. Harsh weather conditions combined with treacherous papa rock that became dangerously slippery when wet significantly extended the timeline. Despite the challenges, Bridge It NZ maintained its commitment to the fixed-price contract, absorbing additional costs rather than abandoning the project during the difficult winter period. The completed bridge, rated to 0.35HN for unlimited stock and tractor use, features an innovative foundation design with deadman anchor systems to protect against seismic forces. With a design life exceeding 100 years, it represents a significant upgrade from the original suspension bridge. Bridge It NZ has built over 300 bridges right across New Zealand, many of them on rural farm and forestry sites. This was the most complex technical design and bridge launch we have ever done and will ever likely do, so it really demonstrated the capabilities of our highly skilled team,” Kim says. “Every conceivable challenge was thrown at us – from near impossible access, to battling harsh winter weather and having to design and execute a bridge launching methodology that we had never attempted before.” TIMBER POSTS & POLES Landscaping Supplies PROUDLY SUPPORTING BRIDGE IT NZ LTD
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