Why is Germany Building Roads for Yesterday's Climate?
As heat waves buckle its Autobahn, Germany is still paving roads for a past climate.
As heat waves buckle its Autobahn, Germany is still paving roads for a past climate. Engineers know how to fix it — so what's the holdup?Multi-day European heat waves with temperatures topping 104 degrees Fahrenheit (40 degrees Celsius) are increasingly leaving their mark on Germany's famed Autobahn — buckling concrete slabs, deforming asphalt, and forcing temporary speed limits.
In early July alone, seven stretches of the country's highways had to be shut down completely for a time.
"The cause often lies in the bitumen — the petroleum-derived binder in asphalt. It's elastic and can soften at high temperatures, from around 60 degrees Celsius," a spokesperson from Autobahn GmbH, the company that manages Germany's highways, told DW. Bitumen is a component in most of the country's roads.
When outdoor temperatures climb above 30C, the surface of dark asphalt can quickly heat to double that or more in the sun and then deform. Using modern, bitumen-free asphalt mixes lowers the risk of such damage, according to Autobahn GmbH.
So, as heat waves intensify and traffic volumes rise, are Germany's roads built to last?
Autobahn need to be prepared for the heat
German roads are "not designed for these stresses at all," said Nina Stelzenmüller. The engineer heads the road construction technology division at the Karlsruhe Institute of Technology (KIT) in southwestern Germany. "The composition of the road surface is based on experience from the last 30 or 50 years," and not on the increasingly noticeable shifts in the climate, explained Stelzenmüller.
At present, road surfaces have to be designed for a temperature range of minus 30C to plus 45C, according to Autobahn GmbH. They are built, the company said, to withstand "the climatic stresses from heat and cold to be expected in Germany."
Yet in some regions of eastern Germany, temperatures could exceed that 45C maximum on certain days by at least 2040. That's according to climate models from Germany's National Meteorological Service (DWD), which assume emissions will remain high in the coming years and that global warming will continue to intensify.
A studyinvolving the research institute of Germany's federal transport ministry (BASt) likewise concludes that climate change is already pushing existing road materials to their limits, and that action is needed. But these findings have not yet translated into binding requirements for updating street surfaces.
Resurfacing as an opportunity: Climate-ready asphalt for the future
Every road resurfaced today needs to withstand temperatures that may only become reality decades from now. But there are plenty of ways to make Germany's vital road infrastructure heat-resistant for the medium to long-term.
A 2019 study, also involving BASt, found that dark asphalt heated up by 7C less when light-colored quartzite was mixed in. The researchers recommended applying reflective surface layers to roads and building in other cooling materials as quickly as possible. The study did not examine the cost or durability of such heat adaptations.
According to Autobahn GmbH, lighter-colored stone is already being used in construction in some cases. The regional availability and cost of such stone also play a role in its use, said the company.
Individual states and cities are also testing and planning light-colored road surfaces, including in the western German cities of Oberhausen and Stuttgart, as well as the eastern state of Brandenburg.
Just scattering light-colored quartzite over the asphalt surface could also help, according to Stelzenmüller, and would be a short-term, feasible approach.
Global models: Water in the asphalt and reflective coatings
Germany isn't alone in facing increasingly hot roads. Infrastructure needs to be adapted worldwide.
Tokyo, for example, already uses reflective, water-retaining road surfaces as standard when resurfacing streets. These can lower the surface temperature by 8 to 10 degrees Celsius. By 2030, some 152 miles (245 kilometers) of roads in the Japanese capital are to be fitted with them.
In Phoenix, in the United States, light-colored coatings have also already been applied to numerous streets. They reflect more sunlight, so absorb less heat. During the day, they were around 6.7C cooler than conventional surfaces. But at the same time, this noticeably warmed the ambient air for passersby.
But Germany, like many other countries, is still a long way from the systematic use of suitable road surfaces to combat heat damage. And even as average temperatures keep rising, the challenge remains that the road surface also has to stay stable even in freezing winter conditions.
As an alternative to bitumen, high-performance binders that can survive both extremes — frost and heat — are currently being developed, said Stelzenmüller.
"For one thing, they're especially elastic, so that at low temperatures they can still bear the stresses caused by the cold. But at the same time they also have a very high strength, which allows them to withstand deformation at high temperatures," explained the engineer.
Policy lags behind the research
A great deal of research on climate-adapted road construction already exists, according to Stelzenmüller.
"But by the time these findings are actually written into regulation and roads are routinely built with them — that's a process that will take years if not decades. I don't expect it can be implemented in the next two or three years," she added.
The heat-ready overhaul of the infrastructure could happen faster if the transport ministry and the road-construction authorities pushed the issue. That's what happened with the tightening of pollutant limits in the development of asphalt mixes.
In 2025, Germany's transport ministry ordered that less-toxic surfaces be adopted "as quickly as possible," even before a new directive on the issue officially took effect.
"There was a real sense of urgency to meet those limits. And here it worked out [quickly], establishing new regulations within a few years," she said.
For road construction that is adapted to climate change and fit for the future, authorities need to take a similar approach, said Stelzenmüller.
"If you put a stronger focus on it, you could certainly have new types of asphalt within a few years," Stelzenmüller added.
By the time of publication, Germany's transport ministry had not responded to DW's request for comment.
This article was translated from German by Josh Axelrod.
(The above story first appeared on LatestLY on Jul 28, 2026 07:30 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).