Tarmac hits back at hot weather study

The report, by UK Climate Impacts Programme, predicts an increase of 1×C to 3×C in average annual temperatures over the next few decades. This, combined with wetter and colder winters and drier summers, says the report, will wreak havoc.

Colin Loveday, director of technology and quality standards at Tarmac, responded: "Asphalt is used on roads and airfields all over the world, including countries that have hotter climates than the UK.

"Whenever we experience hot weather we always hear reports of tarmac melting. The fact is that it isn't the tarmac that is melting. Councils cannot afford to resurface all their country roads so they use a low cost maintenance treatment called surface dressing, consisting of bitumen and chippings. It is a good product and 95% of the time it works, but in very hot weather it can melt," explained Loveday.

Over the last 10 years, the surfacing used on Britain's motorways and trunk roads operated by the Highways Agency has changed.

"We used to use hot rolled asphalt, but during the heatwave of 1976 it came unstuck and industry had to come up with something better. We now use thin surfacings," said Loveday.

However, if future temperatures do soar the way experts are predicting, then Tarmac is more than ready.

"There are certain things we can do to the asphalt to safeguard against hotter weather," said Loveday. "On average, asphalt consists of 95% aggregate and 5% bitumen. There are several different grades of bitumen, from very soft to very hard. By using harder grades we can change the strength of the asphalt. We can also add polymers, but of course every time we add things it bumps up the cost of the product."

Tarmac can also change the aggregate mix, by using less sand and more rock. It is currently undergoing a trial on two military airfields using stone mastic asphalt, which consists of only 15% to 20% sand.