Why roads in Europe melt in 40°C heat while Indian highways survive even hotter summers

As Europe battles intense summer heat, soaring temperatures have exposed the limits of transport infrastructure in countries like the United Kingdom, where roads have softened and rail tracks have warped. In contrast, India's highways routinely withstand temperatures exceeding 40°C, and road surface temperatures above 60°C, with far fewer disruptions.

The contrast is not a matter of luck. It reflects decades of engineering decisions, from the type of bitumen used to the climate conditions roads are designed to withstand.

Built for different climates

At the heart of the difference is bitumen, the binding material that holds asphalt together. Bitumen softens when heated and hardens in colder weather, so countries choose different grades depending on their climate.

India's highways are built to endure prolonged periods of extreme heat. The National Highways Authority of India (NHAI) primarily uses Viscosity Grade (VG) bitumen, including VG-30 and VG-40, which remain stable even when pavement temperatures exceed 60°C, according to the Ministry of Road Transport and Highways' 2024 Bitumen Circular. The guidelines also recommend Polymer Modified Bitumen (PMB) and Crumb Rubber Modified Bitumen (CRMB) for premium expressways, offering even greater resistance to heat.

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Europe, however, has traditionally relied on softer penetration-grade bitumen. These binders are designed to stay flexible during freezing winters and reduce frost-related cracking. During prolonged heatwaves, however, they begin to soften, causing roads to deform or "bleed" bitumen.

Different engineering priorities

The two regions also follow very different road-building philosophies.

India's highway network is designed to withstand both extreme heat and heavy traffic throughout the year. Many newer corridors, including sections of the Delhi-Mumbai Expressway and the Mumbai-Nagpur Samruddhi Expressway, also use rigid concrete pavements, which are more resistant to heat-related deformation.

Much of Europe's road network, by contrast, consists of older asphalt surfaces built for cooler, wetter conditions. Simply switching to harder bitumen is not a practical solution because roads must also survive long winters without becoming brittle and cracking.

Europe's heatwave puts those differences on display

The engineering contrast has become especially visible as Europe experiences one of its most intense heatwaves in recent years.

Denmark recorded its hottest day since records began in 1874, with temperatures reaching 37°C in Ødum. Switzerland touched 38.8°C in Basel, while the Czech Republic logged a record 40.8°C in Doksany. The UK also recorded its hottest June day ever, with temperatures reaching 37.3°C.

The extreme heat has begun disrupting transport networks across the continent.

In Germany, tram services in Leipzig and Nuremberg were suspended after bituminous sealant around tram tracks softened, flowed into rails and switches, and later hardened, making sections of the network unsafe. Rail operators also advised commuters to avoid non-essential travel.

France has faced similar challenges. Prolonged exposure to heat has softened asphalt on roads and pavements, with surface temperatures climbing well above 60°C. As the bitumen binder softens, heavy vehicles create ruts, ripples and "bleeding", where melted bitumen rises to the surface, reducing tyre grip and accelerating road damage.

Heat is also overwhelming hospitals

The heatwave is not only testing transport infrastructure but also placing healthcare systems under immense strain.

Public health authorities, particularly in France and the UK, have reported rising heat-related illnesses and excess deaths, with older adults and people with underlying health conditions among the worst affected.

Hospitals are struggling to cope with growing numbers of patients suffering from heatstroke, dehydration and worsening cardiovascular and respiratory illnesses. At the same time, many facilities, built for Europe's historically milder climate, are grappling with overheating wards and heat-sensitive equipment, including MRI scanners and cancer treatment machines.

Emergency medical services have reported sharp increases in daily call volumes, prompting the World Health Organization to urge governments to invest in climate-resilient healthcare systems as extreme heat becomes more frequent.