Heatwave impacts: can the roads really melt?

It's not just ice and frost on the roads that prompt gritters to mobilise, hot weather can also be detrimental.

As a result of the extreme heat, gritters have been out in force, spreading sand on the roads in order to combat asphalt melting.

Unlike the usual salt spread on roads in winter, which lowers the freezing point of water to prevent ice and frost forming, sand, or stone dust, is used to absorb excess tar.

The melting point of tar is what determines whether the surface will melt in high temperatures; modern day asphalt can withstand higher temperatures than roads that were built several years ago.

It is more common for the older, more rural and also south-facing roads that will see any of this melting, rather than newly resurfaced roads, which is where you are more likely to spot some gritters.

On both roads and rails, the surface temperatures can be around 20C higher than the air temperature under clear, sunny skies.

High temperatures can also impact railway tracks, causing them to buckle as they expand and contract.

Dark coloured surfaces also tend to absorb more heat than lighter ones, allowing the binder that holds the roads together to soften at high temperatures.