The New Zealand industry group, Concrete NZ, has commissioned a report that makes the case for constructing roads of concrete instead of asphalt. The report, produced by consultancy Infometrics and published today, concludes: “…concrete roads are almost always more cost-effective than asphalt roads over a life of 40 years…on average, 17 per cent cheaper…”

The report also points out: “…concrete roading poses significantly less uncertainty in terms of cement prices, than does asphalt in terms of bitumen prices. A further aspect in favour of concrete is that cement is both domestically manufactured and imported whereas New Zealand has 100% reliance on imports for its bitumen supply, with corresponding elevated supply chain risk.”

A chapter of my soon-to-be-published, third volume of New Zealand transport history, The Road Gang, recalls that concrete was seriously considered by town councils to be a suitable alternative to the early forms of asphalt as early as 1918. By then, concrete roads were described as having produced “gratifying results” in America, England, and Europe.

At the time, the cost of the then most used asphalt, Bituco, had increased by 30 per cent and the metal used for the base of most roads was difficult to obtain from quarries because of a lack of railway wagons. Nevertheless, despite the rapid growth of New Zealand cement manufacturers during the twentieth century, as described in The Road Gang, asphalt became the dominant material for road construction –– no doubt due to the predominant influence of the oil companies.     

As an example of a forerunner of today’s Concrete NZ report, I include a 1917 quote of Godfrey Magnus, then of Magnus Motors:
“Concrete roads are the roads of the future, says Mr Godfrey Magnus, who has just returned from the United States…There such roads are being laid down in all parts of the country to meet the demands of the ever-growing motor traffic. He had the great pleasure of travelling over the 500-mile concrete road that joins San Francisco to Los Angeles. ‘It is perfect travelling at last,’ says Mr Magnus. ‘The action of the car is so smooth that you could imagine you were travelling on silk.’”

Despite today’s Concrete NZ report findings and the enthusiasm of a century ago, the use of concrete or asphalt for its Roads of National Significance will, as always, be decided by the Government in favour of the Road Gang members with the most financial and political influence, regardless of any overall benefit to the taxpayer. Expect the bitter-sweet odour of tar before that of metallic concrete.