• Brian Roche is chair of the Aggregate and Quarry Association.

Finance Minister Steven Joyce was on the money when he recently described infrastructure as "all the big unsexy stuff that allows the sexy stuff to happen".

In a country short of housing, subdivisions are sexy, so unblocking the infrastructure bottleneck with a strong dose of Government funding makes sense. It means roads and the pipes and plant needed to supply water and remove waste can go from plans to projects, and pent up demand for housing will be met faster.

Infrastructure enables growth, but what enables infrastructure? Aggregate is right up there. It is even less sexy than infrastructure, but without it roads, bridges, runways, concrete pipes, tunnels and every house that we so desperately need just couldn't happen.

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Aggregate makes up 75 to 90 per cent of all the concrete used in buildings, roads and other infrastructure like airport runways or bridges.

Auckland's Waterview Tunnel consumed 74,500 cubic metres of the stuff, enough to fill 30 Olympic size swimming pools and that's just the backfill. Even more went into the precast panels and more still into the roads and on and off ramps which formed the rest of the $1.5b project.

Current total annual demand in Auckland is 13 million tonnes. This will rise to 16.5 million tonnes by 2031, assuming medium growth, or as much as 20 million tonnes, assuming high growth. The latter is likely given the Auckland Unitary Plan allows for more than 100,000 new houses to be built, mainly in newly developed areas.

Demand is good but only if it's matching supply. Get that out of whack and the greywacke that's widely quarried and used in aggregates will rise in price, adding more costs to our already high cost of building.

Like fruit and vegetables, aggregate is cheaper if bought locally. A truck and trailer load of basic aggregate costs $406 at the quarry gate and $821 once carted 30km away, and over $1000 at 60km. Those extra and often unnecessary transport costs feed into every road and building.

The problem is demand is running ahead of supply. Aggregate production capacity in the Auckland region will be short by 71 million tonnes between now and 2031, or short by 109 million tonnes in a high growth scenario.

Already up to three million tonnes are trucked in from Northland and the Waikato to supplement the 10 million tonne production of Auckland region quarries. This only contributes to Auckland's traffic congestion and unnecessary carbon emissions which could be reduced by sourcing more local aggregate.

This growing supply/demand imbalance will inevitably put pressure on costs unless more thought is given to quarries' role in enabling "all the big unsexy stuff that allows the sexy stuff to happen".

Currently that recognition is limited. One symptom is the $4 million four-year study being funded by the Government into the quality and quantity of aggregate in New Zealand and demand for it. Great idea, but the study is not looking into the squeeze on quarries as cities expand into rural areas.

It is hard to imagine why it is not, given there will be more competition for access to land where the mineral resources are found, and the aggregate needs to be transported from those rural locations to where it is needed.

It's therefore inevitable that people who want a semi-rural lifestyle will come into conflict with quarry operators, even though they are providing the resources to meet the demand for housing and infrastructure for a region. We're seeing that now and the problem will get worse. We cannot let that happen.

The need for aggregate, and the importance of protecting a long term secure source of aggregate, has been recognised by the Auckland Unitary Plan. It identifies regionally significant aggregate resources across Auckland, and it is has given these sites specific zones to enable their development, including some controls on surrounding land.

That is progress, as is the recognition of the need for an integrated national infrastructure plan. What is needed is for it to pay due regard to the critical role played by sourcing local aggregate.

The Aggregate and Quarrying Association met last week in Auckland. We are optimistic about the recognition being given to infrastructure and its importance to our country's economic future, but less so about how we will meet demand. Our national plans must take into account that every road and the majority of buildings will need aggregate sourced locally to keep costs down.

The importance of quarries cannot be under-estimated, so it is crucial to protect existing and future sources of supply.