Book 25, Question 31
How do potholes form each winter and spring?
Water seeps into small cracks in the road.
When it freezes at night, it turns to ice and expands, making the crack bigger. When the ice melts, a gap is left under the pavement. Then cars and trucks drive over the weak spot and break off pieces. After several freezes and thaws, a hole appears. Crews fill potholes with fresh asphalt.