Roads can start to melt or soften at temperatures above the typical melting point of asphalt, which is around 120 to 150 degrees Celsius (248 to 302 degrees Fahrenheit). However, it's important to note that the actual temperature at which roads begin to melt can vary depending on several factors, including the composition of the road surface, the type of asphalt mix used, and the presence of other materials like binders or additives.
In general, hot weather conditions combined with prolonged exposure to direct sunlight can raise the surface temperature of roads significantly. On particularly hot days, the surface temperature of asphalt roads can reach temperatures well above the air temperature. It is not uncommon for road surface temperatures to exceed 60 degrees Celsius (140 degrees Fahrenheit) in certain regions during extreme heatwaves.
When the temperature rises to the point where the asphalt becomes soft or starts to melt, the road can become more prone to deformation, such as rutting or indentation caused by the weight of vehicles. This is why road construction and maintenance take into consideration factors like climate, materials, and engineering techniques to ensure roads can withstand the local temperature variations and traffic loads.
It's worth noting that while roads can soften or deform under extreme heat, they do not completely liquefy like a liquid. Instead, they become pliable and susceptible to damage.