Lifting the 90.5-metre-long arch into place was no mean feat. It's reported to be one of the biggest crawler crane lifts ever undertaken in Aotearoa New Zealand.
WSP Christchurch-based principal bridge engineer Daryn Hobbs was involved in detailed design of the bridge and is the structures lead on the design side during construction.
On site for the lift, he says lifting the arch into place was a major milestone.
“The arch steelwork without the concrete deck is relatively flexible, and we could see certain hangers tighten and loosen as the load path shifted during the lift and set down. We knew that behaviour and the deflections observed were expected, but being there was important to reassure the crane supervisor.”
Commissioned by Wairoa District Council under its professional services contract with WSP, the bridge design prioritises resilience.
Wairoa District Council representative Jamie Cox says the crane lift brought the whole community together - watching the arch fit perfectly into place.
“It was the culmination of eighteen months of planning with WSP. Everything ran to sequence - an absolute credit to the design and project management, and the strong relationship that WSP built with the contractors and client.”
With a design life of 100 years, the new Te Reinga bridge features special foundations that help stabilise the riverbank. The arch was chosen to address slope stability risks, with its single span eliminating the need for a pier in the riverbed. There is more clearance for floodwater and debris, and the hangers in the bridge arch can be removed and replaced without affecting the bridge’s ability to carry traffic.
In a nod to low maintenance design, the arch is made of weathering steel, which, over time, forms a protective rust layer.
Bridge experts from WSP's Christchurch, Nelson, Wellington, Napier, Gisborne, Palmerston North, and Auckland offices have been involved in the project.
With the arch now snugly in place, next up comes finishing touches to the bridge abutments, construction of the bridge deck, surfacing, and erection of barriers. Fourteen-meter concrete ‘land spans’ are also soon to be installed, connecting the bridge's approach roads to the main span.
Daryn says key to the success of the project so-far has been early contractor involvement during the design process, and, for November's milestone crane lift, collaboration and teamwork between WSP's bridges team and contractors QRS and Brian Perry Civil, crane provider Smith Cranes, and steel fabricator Eastbridge.
Completion is scheduled for early 2026.
Once the ribbon is cut, a temporary Bailey Bridge that has been servicing the local community since Cyclone Gabrielle is expected to be removed.
For more information about the recent crane lift, visit Wairoa District Council's website.
