Eventually, the asphalt layer over these divots collapses, creating the traffic hazards we call potholes. Potholes can cause significant damage to a car’s suspension system or tires if the driver fails to avoid them. Potholes can also fill with water, obscuring any other hazards they may contain. Even in places where the air temperature rarely falls below freezing, excessive rainfall or flooding can also cause potholes to form.
Road maintenance crews have two different forms of repair methods for potholes. These repairs are roughly similar to a dentist using either a temporary or permanent filling material for cavities. During the winter months, potholes receive what is known as a cold winter mix. This is a temporary fix consisting of a soft asphalt poured into the potholes after they have been cleared of debris. A layer of gravel may be added to increase strength and stability, but the potholes are often expected to reappear by spring.
A more permanent fix for potholes is called a hot summer mix. This combination of roadgrade asphalt and aggregate is designed to last for years, but it can only be applied during dry, warm weather. When road crews use a hot summer mix to repair potholes, they often reroute traffic around the worksite and spend more time preparing the road surface for the patch. The finished layer of new asphalt is usually compacted to match the level of the road, rendering it nearly invisible.