A major bridge on Te Ahu a Turanga: Manawatū Tararua Highway that will allow road users access across the Manawatū River has been completed.
The completion of the concrete deck on the 300-metre-long Parahaki Bridge means both banks of the river are now connected.
The balanced cantilever bridge is now considered ‘structurally complete’ from an engineering perspective, although crews will be continuing to work on it, including the installation of barriers, a viewing deck, drainage and the laying of asphalt.
These are expected to be completed early in the new year.
NZ Transport Agency Waka Kotahi project spokesperson Grant Kauri says the bridge has a width of about 30 metres, making it one of the widest bridges of its kind in the southern hemisphere.
“The Parahaki 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.”
“It has been a challenging structure because of its location in a fast-flowing river that’s also on a fault line. It’s also located between the Ruahine and Tararua ranges, which creates a wind tunnel.
"When the team started working on the foundation piles, they found the ground conditions were quite difficult. It took a few months longer than expected to get the first piles in the ground.”
Piling was complete by mid-2022 and by December that year the first pier was finished.
The balanced cantilever method involves constructing the bridge deck in segments, out from the piers.
The concrete segments are poured in situ (in place), rather than being precast and then lifted into position, because the segments would be too heavy to be lifted by crane.
“This is the culmination of years of hard work by many people. We would never have been able to do this without the expertise of all those who have contributed, I’m truly grateful to all the teams who’ve been involved to date.”
Construction of the bridge deck began in September 2023 with the installation of the first form traveller, a pair of streel frames that support the concrete pours. It took the team 13 months to construct all 54 bridge deck segments.
Te Ahu a Turanga construction started in January 2021 and is expected to be completed in mid-2025.
The road will replace State Highway 3 through the Manawatū Gorge, which was closed in 2017 due to landslides.
