Swedish roads at risk of “bleeding asphalt” in heatwave

The Swedish Transport Administration has warned drivers of the risk of “bleeding asphalt” as temperatures approach 35°C, urging caution on the roads.

Hot weather can cause asphalt to soften, creating slippery conditions, according to Jan-Erik Lundmark, the agency’s national coordinator for road surfaces. He noted that the phenomenon can occur suddenly and is difficult to predict.

Newly laid asphalt—less than two years old—is particularly vulnerable, though the issue can arise elsewhere, such as on south-facing slopes where sunlight is more intense. Drivers should watch for shiny surfaces or spray from vehicles ahead, signs of asphalt bleeding, Lundmark said.

While no cases have been reported yet, the agency is monitoring roads and relies on public tips. Lundmark advised drivers to reduce speed and maintain distance, especially during holidays.

Bleeding asphalt occurs when heat softens the binding agent in the pavement, causing it to rise and form slick, dark patches. The hazard increases if rain coincides with the bleeding.