44 | INFRASTRUCTURE Te Ahu a Turanga Alliance T T Karen Phelps Project presented significant challenges The Te Ahu a Turanga Manawatū Tararua Highway project presented significant challenges for contractors including moving about 6.5 million cubic metres of earth over challenging terrain and building one of the Southern Hemisphere’s widest balanced cantilever bridge over the Manawatū River. Now it’s won category 5 for projects valued over $100 million in the 2025 CCNZ Hirepool Construction Excellence Awards recognising the extraordinary achievement of constructing the project. The project has restored a crucial transport connection that was severed eight years ago when the original Manawatū Gorge road was permanently closed following devastating slips. Grant Kauri, Waka Kotahi NZ Transport Agency Owner Interface Manager, says the 12-kilometre four-lane highway, which opened ahead of schedule in June 2025, represents a triumph of engineering innovation and collaborative partnership with the alliance comprising New Zealand Transport Agency Waka Kotahi, Fulton Hogan, HEB Construction, Aurecon, WSP and five iwi partners. A key part of the project is Parahaki Bridge – one of the Southern Hemisphere’s widest balanced cantilever bridges - spanning 300 metres across the Manawatū River at a height of 30 metres. “It has been a challenging structure because of its location in a fast-flowing river that’s also on a fault line,” says Grant. “The bridge required innovative temporary staging across the Manawatū River using hollow steel piles installed 11 metres above the 100-year flood level. The bridge is unique in that it’s not straight and flat - it has a curve, a camber and a gradient, so each bridge deck concrete pour was specifically designed and highly complex.” The Eco-Viaduct was another particularly Manawatu Gorge lookout on Parahaki Bridge. Supplying highly skilled tradespeople to the civil construction industry Proudly Supporting Te Ahu a Turanga Alliance Contact Us Adam Travers-Bishop 021 733 708 Alexandra Goddard 021 733 709 admin@megastructures.co.nz complex aspect as drilling revealed artesian groundwater pressure reaching 27 metres above ground level, far exceeding the anticipated 3-5.5 metres. “Installing the planned staging with the high artesian pressures was too risky and needed significant changes to piling methodologies,” says Grant. “The solution required 14 months of continuous de-pressurisation using eight de-watering wells operating around the clock.” He says environmental protection remained paramount throughout construction. The project achieved exemplary environmental management scores from Horizons Regional Council, with no major incidents reported. Stream diversions, sediment retention ponds and the relocation of over 3,000 fish demonstrated the commitment to ecological preservation. The discovery of the at-risk Meterana Grandiosa moth led to careful relocation T T to page 46 OFFROAD FENCING For all your fencing and lifestyle Block requirements Leave the hassle of fence installation to our skilled professionals. With years of experience, we ensure your fence is installed with precision and care, making it stand the test of time, and always becoming a staple piece of your property. We offer rural, residential, commercial, and pool fencing. As well as post-ramming, retaining walls, pole sheds, repair work and more. Contact Us offroadfencing@gmail.com | 0272 366 139 | offroadfencing.co.nz R u r a l F e n c i n g | U r b a n F e n c i n g | S e c u r i t y , C o mm e r c i a l | P o o l F e n c i n g
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