Case for concrete roads launches in Waikato

Transport Minister Simeon Brown launched the 'case for concrete roads' in the Waikato. Photo / Sylvie Whinray

A new economic report shows concrete roads are well suited for high-intensity traffic and are more cost-effective in the long run, leading to the launch of the ‘case for concrete roads’ in the Waikato on Wednesday.

The report showed significant money and time could be saved if the Cambridge section of the Expressway to State Highway 29 at Piarere was constructed using concrete.

The case was launched by Transport Minister Simeon Brown at an event in Claudelands, Hamilton accompanied by the report commissioned by Concrete New Zealand and prepared by consultancy Infometrics.

It showed that concrete roads were 17% cheaper over the whole of their lifetime, reduced carbon in the atmosphere, and significantly reduced the cost and frequency of road maintenance.

It built on previous reports from 2013, 2018, and 2020, to argue a case for using concrete in road construction.

Infometrics chief forecaster Gareth Kiernan said the report looked at roading costs nationwide and considered research overseas.

“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,” he said.

Hamilton Mayor Paula Southgate.

“Lifetime carbon emissions for concrete roads may also be better than tar seal because concrete reabsorbs carbon dioxide.”

Kiernan said lack of capability has been a major limitation for concrete roading in New Zealand, and government could play a role to overcome it.

“For example 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.”

Hamilton Mayor Paula Southgate said the city was the fastest growing centre in New Zealand and the council must consider new and innovative approaches to deliver infrastructure.

Southgate said roller compacted concrete (RCC) was trialled 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.”

Concrete New Zealand chief executive Rob Gaimster said concrete roads should complement existing road types, and were best used in areas with high traffic densities and high stress from heavy vehicles.

He said several examples where concrete would save money and time included 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.

Gaimster said the report showed concrete roads could have a lower carbon footprint over whole-of-life than asphalt if carbon uptake is considered.

Emissions associated with concrete roads can be even further reduced by using low carbon concrete, and concrete can also be recycled.

National Road Carriers Association chief executive Justin Tighe-Umbers said concrete for some projects was a “no-brainer”.

“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.”

He said concrete roads are “rigid” and can reduce fuel consumption, and don’t melt as summer approaches.

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

The 2024 report summarised international comparisons of concrete and asphalt roads, showing concrete roads “are almost always more cost-effective than asphalt roads over a life of 40 years”.

Costs are different in countries due to differing labour and other input costs, types of asphalt and concrete technology, the rate when calculating costs over whole of life, and the differing life span of roads.

Infometrics drew on this data, and available New Zealand data, to run 20,000 computer simulations of roading construction and maintenance costs in New Zealand.

The result is a 12% to 23% advantage in costs to concrete over asphalt for the central 90% of the distribution of results. The weighted mean is a 17% cost advantage to concrete.