Permanent bridge and large culvert rebuilds

Feasibility study

A feasibility study has been conducted to understand the unique engineering challenges at each potential bridge site, with the aim of proposing practical bridge concepts.

The top three priority bridge sites are Puketapu, Matapiro, and Waiohiki/Redclyffe. Puketapu and Matapiro have financial and time constraints crucial for reconnecting communities quickly.

The feasibility study provides a starting point, and we will be incorporating input from both mana whenua and the community into the bridge design process. This collaborative approach will ensure the final design meets engineering standards and community needs.

Design considerations

The destroyed bridges in Hastings District were built before the 1960s. They were designed back when our knowledge and methods for designing, building, and maintaining bridges were not as advanced as they are today. We've made substantial advancements in these areas, which guide us in planning and building new bridges.  Today's design standards can handle even extreme weather events like Cyclone Gabrielle.

 The design considerations for the replacement bridges can be summarized as follows:

• Increased freeboard clearance: The new bridges will have a higher freeboard clearance to provide greater space between the bridge and the water during flood events and include climate change adjustments using the current best estimates.
• Longer spans and fewer columns: Whenever feasible, the bridges will incorporate longer spans and fewer columns in the water. This design approach aims to reduce the risk of flow blockage caused by debris and slash during flood events. However, earthquake resilience is still a major consideration.
• Circular columns: Circular columns will be considered in the bridge design to minimize the chances of debris getting trapped at the piers. This helps maintain the river's flow and mauri, or life force.
• Traffic and pedestrian capacity: The capacity to accommodate both vehicular traffic and pedestrians will be a key consideration in the design of all bridge rebuilds, ensuring functionality and safety for all users.

Old (red) vs new design to current standards - Puketapu example