46 | New bridge underway at Kakanui construction Spanning Kakanui River in Kakanui, a coastal settlement south of Oamaru, the now very tired old bridge was opened in October 1899, and is currently being replaced. Waitaki District Council & Concrete Structures: Kakanui Bridge T T Russell Fredric “It has been a structure that the council has acknowledged for the last 22 years that was in imminent need for renewal, and in more recent times we’ve been looking at how it’s got a very short lifetime because of its age deterioration, but also increasing traffic sizes, volumes and the challenges and risks of an ageing bridge structure.” REGIONAL DEVELOPMENT Even the most optimistic early settlers driving their horse and cart over Kakanui’s newly built timber bridge could barely have conceived it lasting 126 years into the future. Spanning Kakanui River in Kakanui, a coastal settlement south of Oamaru, the now very tired old bridge was opened in October 1899, and is currently being replaced following the contract being awarded to Concrete Structures, a leading precast manufacturing and civil engineering company with a nationwide presence. Kakanui is within the Waitaki District Council region, which covers 7100 square kilometres, extending from part of the South Island’s east coast to close to Aoraki/Mt Cook at the northwest extremity of its boundary. Kakanui Bridge is part of the State Highway 1 resilience route, and replacing it will ensure an alternative route is available should the main highway be affected by flooding or other incidents. Waitaki District Council project manager Mike Harrison says, despite the bridge being an asset of national, regional and community importance, the district has waited a long time for it to be replaced. “It has been a structure that the council has acknowledged for the last 22 years that was in imminent need for renewal, and in more recent times we’ve been looking at how it’s got a very short lifetime because of its age deterioration, but also increasing traffic sizes, volumes and the challenges and risks of an ageing bridge structure.” The existing structure has a heavy vehicle weight and speed restriction of 80% of a class 1 bridge at 10km/hr. “If we didn’t replace it, that was going to probably change to 70% of class 1, which means the likes of fire appliances fully loaded would have trouble getting across it,” Mike says. The total cost of its replacement and the association works will be $11.06 million, funded 57% by NZTA and 43% by Waitaki District Council. The new, 162-metre-long, single-lane bridge will be a fully concrete structure with seven spans, suitable for heavy goods vehicles, as well as having a separated pedestrian/cycle path. It will be built upstream of the existing bridge, with the road being realigned on both sides. This will involve the closure of the existing boat ramp to allow construction. Concrete Structures has considerable experience in building bridges, and offered an alternative design to what was specified in the council’s tender, which is what actually made it happen,” Mike says. “Their alternative tender was so impressive that the council was very pleased to get into partnership with them. “Even just 18 months ago it was still questionable if we could actually bring it together, but through everybody pulling together it’s made what was beyond our reach a reality. They saved us an awful lot.” Oamaru company Whitestone Contracting is undertaking the civil works, including the road approaches, and Concrete Structures has employed some local labour as part of its workforce. A replacement boat ramp will be built at the site of the old Kakanui bridge abutment as part of the project. The current Kakanui Bridge will remain in place until construction is finished, and when it is deconstructed it is hoped the timbers can be reused in the community, depending on their condition. The new bridge is expected to be completed late May 2026, and will be the town’s third – the first opened in 1871 and lasted 28 years. Proudly supporting Waitaki District Council & Concrete Structures www.whitestone.co.nz | 0800 109 101 | info@whitestone.co.nz
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