Why does the material used in road construction in other hotter countries (eg Spain) not suffer the same problems in extreme heat?

• In Mediterranean countries road materials are designed to cope with a different temperature range typically -5c to 50c degrees, whereas the UK is typically -20c to 30c degrees. As result of previous heat waves in the 1970’s and 80’s, the specification for road materials was improved to include poly-modified binders which are far more resilient to higher temperatures.
  
  
• A lot of the current damage that is happening on the local road network is caused by older road surfacing materials that are less resilient to heat damage that the newer products. 

What air temperature would it need to reach for roads to melt/sustain damage?

• When the air temperatures get above 30c degrees the road surface temperature gets up to 50c degrees as the dark road surface absorbs heat and this can cause the bitumen in the road surface material to melt.

Can friction from road users i.e. vehicles, or any other factors, influence at what air temperature roads melt or are damaged?

• Busy roads can cause more stress which will exacerbate the damage.

When roads melt and/or sustain damage, what happens to the material structurally when they reach that temperature?

• Roads melt because the bitumen softens and then loses it adhesion to the stone

Is this an impact of under investment in maintenance?

• Damage to concrete roads and runways can often occur if the built-in expansion joints have not been properly maintained and this can cause the road surface to buckle. CIHT has consistently called for an increased and consistent investment in local highway maintenance.

Improving Local Highways

CIHT has proposed four recommendations to the UK government that would create a new vision, unlock funding and a renewed focus on the local highway network over the next ten years.

See here for more details