A new report commissioned by Concrete NZ makes a compelling case for reconsidering the material New Zealand uses to build its roads. According to the Infometrics analysis, concrete roads cost on average 17% less over their whole-of-life cycle than asphalt alternatives — and also carry a lower embodied carbon footprint once maintenance is factored in.
The report, The Case for Concrete Roads, builds on three previous studies dating back to 2013. The consistent finding across all four is that concrete’s higher upfront cost is outweighed by significantly lower maintenance expenditure over a road’s operational life.
The Economics of Road Surfaces
Asphalt roads are cheaper to lay initially, which is why they dominate New Zealand’s roading network. But they require resurface cycles every 10 to 15 years, depending on traffic volume and climate conditions. Concrete roads, by contrast, can last 40 years or more with minimal maintenance — a difference that accumulates to millions of dollars in savings for roading authorities over time.
For a country with an aging roading network and significant infrastructure maintenance backlog, the whole-of-life argument deserves serious consideration. The National Land Transport Fund spends a substantial proportion of its budget on maintenance and resurfacing of existing roads — budget that could be redirected to new capacity if the underlying asset lasted longer.
The Carbon Angle
Concrete production is carbon-intensive — that much is well established. What the Infometrics report highlights is that when you account for the full lifecycle including the fuel burned by maintenance vehicles, the carbon from production and transport of asphalt resurfacing materials, and the operational disruption caused by road closures, concrete’s carbon footprint over 40 years compares favourably.
This is a nuanced argument that requires lifecycle thinking rather than a simple comparison of production emissions. As New Zealand works toward its emissions reduction targets, the construction and infrastructure sector will need to apply exactly this kind of analysis to material selection decisions.
Barriers to Uptake
Despite the evidence, concrete roads remain rare in New Zealand outside of airport runways and some industrial areas. The barriers are partly financial (higher upfront cost creates budget pressure), partly procurement (road agencies are set up to specify and contract for asphalt), and partly cultural — the roading industry knows asphalt, and change requires evidence-based advocacy.
Concrete NZ argues that the evidence is now strong enough to warrant a formal review of road surface specifications, particularly for high-traffic arterials and motorways where the whole-of-life maths is most favourable. Whether the New Zealand Transport Agency and local road authorities respond remains to be seen.