Quarrying & Mining Magazine
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Should I seal?

Downer MetService NZ QM Magazine Featured Image

A chance meeting between a Downer scientist and a weatherman has led to road sealing success. GARETH THOMAS explains.

The technical team at Downer-owned Road Science had cracked it. After several years of laboratory testing in Mount Maunganui, specialists developed their own emulsified bitumen.

Downer MetService NZ QM Magazine Content Image
Downer MetService NZ QM Magazine Content Image

It does everything the researchers wanted it to do. It can be applied at lower temperatures than hot or cutback bitumen, it adheres to chip better than other products, and health and safety is improved for the roading gangs.

But there was one vital ingredient missing. How would the risk of run-off in bad weather be managed?

“We felt that after six years of development we’d solved every problem except one. And that one was the fact that bitumen emulsion is a water-based system. And in a water-based world you’re always going to have the possibility of rain catching you out,” says Road Science technical manager John Vercoe.

The problem was solved by being in the right place at the right time.

“I was attending a conference in Nelson and we had a stand there. And just by sheer luck the stand next to us was MetService,” recalls John.

He was baffled by the appearance of the state-owned enterprise at a roading conference. A brief discussion with the man from MetService, Peter Fisher, revealed how weather forecasting was being used in a programme for the deployment of de-icing chemicals on Arthur’s Pass.

That piece of enlightening information proved to be inspirational for John.

“Suddenly I thought … maybe we could use the same concept for our bitumen emulsion because right at that same time I was struggling to solve this last problem of wash-off,” he says.

Weather prediction programme

A partnership between MetService and Downer was born and a new online weather forecasting tool was created. They called it Should I Seal, or SIS.

“We gave the Downer contract managers access to SIS. They are all currently using it as a way to plan their work,” says Road Science product development manager Anna D’Angelo.

“They would look at this tool to see whether it is safe to use and work with the bitumen emulsion. We developed the tool to avoid the risk of wash-off. The risk when using bitumen emulsion is that if it rains after it has been applied there is the risk of this brown water wash-off,” she says.

Environmental factors

To understand the tool and its uses you could think of it as an intelligent weather forecaster. It is, plus much more. Researchers have developed an algorithm to factor in temperature, humidity and the possibility of rain’s effect on bitumen.

SIS is designed specifically for roading contractors and gives more control to the sealing teams.

Today all Downer contract managers charged with laying chipseal with bitumen emulsion are armed with the SIS portal on their smartphone or tablet. Another advantage of Should I Seal includes smoother workflow for the crews.

“They’re using it as a way to plan. They can use it as a way to order the product and decide also which site they are going to seal,” according to Anna.

Feedback on the forecasting technology from the foremen is positive, following initial hesitation from some Downer roading gangs.

“We had very good support from them and they had asked us to improve the tool. The other step was to roll it out to the rest of the Downer people.

“At the beginning some people were sceptical and they kept looking at other tools, such as forecasts which are only weather. But soon they realised our tool, SIS, was not just a weather forecast but a product-based forecast.

“It says when to go out, how much to spray, and what product to spray on a particular day, and at what particular time,” says Anna.

Curing time is the key

At this stage SIS is only used by Downer. Its competitors are using conventional weather forecasting. Although they could choose to develop the technology to match SIS, it is estimated it would take them a least a couple of years to perfect a product-specific package with MetService. That gives Downer the edge, says John Vercoe.

He says SIS puts the Downer workers in a commanding position. “It tells them absolutely when to stop. Usually they have to stop well before the rain event because the product has to cure and if the humidity is high that curing period could be a number of hours.

“So automatically it takes out of their calculations the estimate in their head of how long they’re going to have to give themselves before they have to finish,” adds John.

The bosses have every confidence in Should I Seal, and their praise of the product is having a ripple effect among the staff.

“For young guys coming in they’ve got something to fall back on. In other words if they go out there and spray and they get caught with a wash-off they can also hold it up to the management and say ‘hang on SIS said it was okay to go’,” says John.

Downer is not stopping there in its business relationship with MetService. The weather forecaster is said to be excited about Should I Seal because there is potential to develop similar technology for other industries, such as concrete laying or orchard spraying.

Road Science and Metservice are already looking to the future. John Vercoe says SIS is just starting and there will be a next generation of the technology.

“Most phones have GPS and what we’d like to do for the SIS programme is to automatically know the location of where you’re standing and select the relevant weather forecast station to give the most accurate prediction.”

John says by tapping in to the nearest local MetService weather station the accuracy of forecasting for road sealing teams will be even higher.

And if that smart solution is not captivating enough, the next step might involve using mobile weather stations mounted on the back of trucks for pinpoint precision.

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