Why Cork City roads withstand heat as rural routes suffer damage

Cork City Council said it uses road surfacing materials with a higher melting point than standard tarmac, as soaring temperatures in recent weeks caused damage to roads in other parts of the county

The high temperatures led to damage to many roads, as the dark road surface absorbs heat and can bring the surface temperatures to 50C, the melting point for the standard tarmac. File picture: Brian Lynch

Cork City Council has said the materials it uses for roads has a higher melting point than the standard tar used in rural parts of Cork, where damage has been reported.

Numerous status-yellow high-temperature warnings have been in effect in Cork in recent weeks, as the mercury neared 30C in parts of the county.

The high temperatures led to damage to many roads, as the dark road surface absorbs heat and can bring the surface temperatures to 50C, the melting point for the standard tarmac.

Melting tar can lead to cars skidding as it softens and oil rises to the surface or cause damage to tyres.

Surface temperatures above 40C were recorded by TII on a number of roads across Co Cork on Friday:

• N72, Fermoy: 51C 
• N71, Leap: 49C 
• M8, Mitchelstown: 47C 
• N20, Charleville: 46C

Asked  why the city was not experiencing the same issues as Cork County Council with regard to melting roads, a Cork City Council spokesperson said the material used for city roads had a higher melting point than what is commonly used on more rural roads.

They said: “The melting of roads is not a significant issue in Cork City as the vast majority of our roads and streets are surfaced with stone mastic asphalt or hot rolled asphalt, which has a higher melting point than a thin tar layer on surface dressed roads.” 

It comes as Padraig Barrett, Cork County Council’s director of roads and transportation, said last week that the local authority may need to look at a more expensive material for its roads.

Council crews have had to treat numerous roads across the country with sand and grit as tar is melting in surface temperatures exceeding 50C as a result of the ongoing heatwave.

Mr Barrett suggested that, as heat-related damage to roads becomes more frequent and scientists warn temperatures will continue to rise, authorities should consider moving away from standard cationic bitumen and instead use a material known as premium polymer modified emulsion (PPME) for road surfacing.

It can withstand road temperatures from minus-15C to 60C, but it costs up to 20% more than the standard materials.

This would mean significantly more road funding would be needed, as there are 12,200km of roads across Co Cork, the largest road network of any local authority, which has repeatedly said that it receives “one of the lowest allocations per kilometre” nationally.