Expect fewer flood closures on a low-lying section of SH1 through the Kakanui River flood plain near Maheno, says NZ Transport Agency Waka Kotahi (NZTA). The flood-prone section of the main highway has had $3 million of engineering improvements made in recent months, aiming to keep the road open and above water level, even in a one-in-50-year-flood.

The project, built by Oamaru-based Whitestone Contracting, took seven months and delivered on behalf of the Government and NZTA, as part of nationwide work to reduce the risk of natural events such as floods closing key highways.

Keeping communities and businesses connected during flood events is the aim, says NZTA Project Manager Jason Forbes.

The most effective, efficient, and affordable option of those investigated to reduce the flood risk at this location, was retaining the existing highway layout, and raising the road height by slightly over a metre. NZTA modelling showed this would reduce the amount of floodwater covering the highway and result in little if any increases in water on nearby property, given concerns about flooding in this low-lying area.

Jason Forbes commended the Whitestone team for their commitment to getting this project completed ahead of the winter period, while meeting all key requirements and coming in under budget.

What the project does:

• Provides greater safety with a wider road and three hundred metres of safety barrier on its western side.
• Reduces disruptive floods by raising the height of a 350-metre section of SH1 through the Kakanui River flood plain.
• Delivers new road surfacing and markings.
• Offers safer and better access to the historic Clarks Mill.
• Builds a new bridge structure over the existing historic Mill Stream Culvert.

The benefits:

• Fewer flood-related disruptions, with the highway passable for traffic during one in 50-year floods.
• Reduced flood-related delays on the main highway between Christchurch and Dunedin.
• Improved road access to keep communities and businesses connected during major flooding.
• Greater resilience on a flood-prone, low-lying section of SH1 between Oamaru and Dunedin.

More information can be found here: https://www.nzta.govt.nz/projects/sh1-kakanui-flood-protection-improvements/

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