In our winter resilience insights, we’ve looked at how winter conditions can place pressure on infrastructure and why resilient outcomes often depend on the decisions made well before the storm arrives. From stormwater networks and transport routes to ageing assets and community infrastructure, the series has focused on the importance of planning early, understanding risk and designing infrastructure that can respond when conditions become more challenging.
That applies whether you’re planning a new development, upgrading an existing asset or looking at how a wider network performs under pressure. For councils, developers and asset owners, understanding these factors from the start can support more informed decisions and help reduce risk, disruption and long-term cost.
With that in mind, here are a few key areas to consider:
- Know the site before committing to the design. A good understanding of the site makes a big difference. Survey, geotechnical investigations, hydrological modelling, flood mapping and local knowledge all help build a better picture of how a site may behave in winter.
- Design for exceedance, not just compliance. For example, ask what happens when rainfall exceeds the design event, when drains block, when river levels are high, or when saturated ground reduces stability.
- Protect critical flow paths. Overland flow, secondary drainage routes and maintenance access are essential parts of resilient design.
- Integrate civil and geotechnical thinking. Drainage, pavements, slope stability, retaining structures, foundations and earthworks all perform differently in wet winter conditions, so it helps to consider how they influence one another.
- Build resilience into renewals. Renewals and upgrades are an opportunity to improve how existing infrastructure performs. Infrastructure New Zealand has called for renewals and upgrades to incorporate climate-resilient design and increase system capacity for higher drainage volumes.
- Consider nature-based and low-impact solutions where appropriate. Where site conditions allow, permeable surfaces, swales, detention areas and green infrastructure can help reduce runoff, improve infiltration and support better environmental outcomes. Infrastructure New Zealand has identified greener, more permeable urban environments, including grass swales, as part of climate-resilient design.
The opportunity
Winter will always test New Zealand infrastructure but with the right data, smart design and more integrated delivery, communities can help reduce disruption, protect assets and support better long-term investment decisions.
For Davis Ogilvie, designing for winter means designing for real-world conditions: the rain that arrives before construction is finished, the saturated ground beneath the road, the river sitting high at the outfall, the ageing culvert no longer performing as intended and the community relying on infrastructure to keep working when conditions are at their worst. That is where practical engineering matters most.
