How do potholes form? Why are they more prominent in the spring?
Potholes form with the expansion and contraction of water after it has entered into the subsurface of the pavement. When water freezes, it expands, taking up more space under the paving, which then causes cracking. As temperatures increase, the water then thaws, leaving gaps or voids in the subsurface of the pavement. The voids allow for more water to enter under the pavement, creating a vicious freeze/thaw effect, which eventually weakens the pavement. As the weight of cars and trucks pass over the weak spot in the road, pieces of the roadway material weakened by the freezing and thawing effect get displaced or broken down from the weight, creating the pothole.
This process often takes place in the spring as moisture is often trapped in the pavement following the winter or even new storms and temperatures fluctuate from day to night, freezing and thawing the water.