Could Concrete Roads Be the Future of New Zealand’s Infrastructure?

A new Infometrics report says that concrete roads are on average 17% cheaper over whole-of-life, reduce embodied carbon in roading. Commissioned by Concrete NZ, The Case for Concrete Roads builds on three past reports, the oldest from 2013. Concrete roads could significantly reduce the cost and frequency of road maintenance.

“The report shows that although concrete roads cost more to build, savings can amount to millions of dollars for central government and councils as maintenance costs are up to 62% lower,” says Infometrics chief forecaster Gareth Kiernan. “Lifetime carbon emissions for concrete roads may also be better than tar seal because concrete reabsorbs carbon dioxide.”

He says that the lack of capability has been a major limitation for concrete roading in New Zealand, and that the Government could play a role in overcoming this hurdle by funding a pilot project. “Expanding the industry’s capability to be able to build concrete roads, with their extra resilience, could also be increasingly important as heavier electric vehicles become more common.”

About half of American highways are concrete-built. Concrete NZ chief executive Rob Gaimster says concrete roads should complement existing roading typologies; concrete roads are best used where traffic density and heavy vehicle stress is high. “We can see a number of stretches of road where concrete would save money and time, such as Auckland’s Port Motorway, the Cambridge section of the Waikato Expressway to the intersection of SH1 and SH29 at Piarere and SH1, North of Levin.”

National Road Carriers Association CEO Justin Tighe-Umbers says concrete roading is a no-brainer for some New Zealand projects. He says concrete roads are rigid so can reduce fuel consumption, and won’t melt as summers grow hotter. “The whole-of-life economics present a compelling case for this durable, low-maintenance solution. It should be considered for the new Roads of National Significance and Roads of Regional Significance to provide a lower total cost of ownership.

“While concrete will not suit every roading purpose, it certainly deserves more consideration than has occurred to date in New Zealand.”

Hamilton mayor Paula Southgate says her city must look at innovative approaches to deliver infrastructure needs. “Innovation, quality work and better cost efficiency are important principles in all construction projects we do in Hamilton city.

“We recently trialled Roller Compacted Concrete (RCC) on Arthur Porter Drive, a busy industrial road with unique construction challenges. The early results are promising, and shows us that concrete is a smart and sustainable choice for future projects, though of course each new project will need to be assessed individually.”

The Case Against Concrete Roads

It makes sense that the industry association for concrete proposes a strong case for concrete roads. The New Zealand Transport Agency says that although concrete roads were built in New Zealand

between World War One and World War Two, they are currently not being used for many reasons. They are difficult to maintain where services such as water, gas and sewers are located underneath. New Zealand is susceptible to long-term earth movements which concrete roads don’t handle very well. Finally, they are more expensive than asphaltic concrete and tend to be more noisy than asphaltic concrete without a noise-absorbing surfacing.

“On medium to high-traffic highways, the best base course layer is good-quality crushed local stone (aggregate),” the NZTA website reads. “Where this isn’t available, we use lime or cement to improve the strength of the crushed stone. For even heavier traffic, such as on motorways, we use an asphaltic concrete (bitumen) mix instead of stone.”

Concrete roads have many disadvantages. Take how the upfront costs for materials and construction can be two to three times higher than asphalt. Further, concrete is less forgiving than asphalt when it comes to flexibility and adaptability. New Zealand is prone to seismic activity and so uses asphalt predominantly as its flexibility allows it to better withstand ground movement. Japan uses asphaltic pavements for up to 90% of its roads for the same reasons.

Concrete production is a major contributor to global carbon emissions. Cement, the primary component of concrete, accounts for approximately 8% of global CO₂ emissions. While advancements in “green concrete” technology show promise, they remain costly and are not yet widely available. Quarrying raw materials like limestone and gravel for cement production disrupts ecosystems.

Concrete roads have compelling long-term economic and environmental benefits, especially for high-traffic and heavy-vehicle routes, but aren’t a one-size-fits-all solution. There are many glaring challenges: seismic resilience, upfront costs, and environmental concerns. A hybrid approach could be the answer to New Zealand’s diverse infrastructure needs.

Concrete roads could be a useful addition to current asphaltic networks, especially in places with heavy traffic or harsh weather. In less demanding or geologically active areas, asphalt may continue to rule because of its affordability and adaptability. A mixed future is likely, as policymakers, industry leaders, and researchers collaborate to assess the feasibility of more concrete roading nationwide