Breakdown: Why weather can make potholes worse

Breakdown: The science of potholes

MEMPHIS, TN (WMC) - Potholes. They can be a nuisance when traveling around city streets. Sometimes they even seem like the form out of nowhere. Did you know that the weather can cause these potholes to form and make them worse?

In this episode of the Breakdown, we will explain how potholes form and why the change in weather can make those potholes worse over time.

Weather and Potholes
Weather and Potholes (Source: WMC Action News 5)

Roadways and highways are usually constructed in layers. The top layer is water resistant and curved to drain water off the road and onto the shoulder.

As the rubber hits the road and cars travel along the highways and byways, it will cause fatigue of the road surface. This will then cause cracks and breaks in the surface of the roadway.

Water will then seep in through the cracks on the road surface, collecting underneath and softening the road base.

As the water collects, it will then freeze when it’s cold outside and that will expand as it freezes. That will force the road surface upward, almost like a bubble under the pavement. The more traffic there is on that point, the more it will stress the roadway.

The sun will then then help dry up the water that seeped into the ground. Remember the dark colored roadbed helps absorb the suns rays and dry out the water. This will then create a hole under the road surface.

The weight of the cars, trucks and tractor trailers on the roads help collapse the road surface into the hole. Where this collapse forms, a pothole is then formed, and traffic will continue to expand the hole.

The change in Mid-South weather can help create more and more potholes across the region -- mainly when we get nighttime temperatures below freezing and daytime temperature above freezing.

This temperature cycle results in several freeze-thaw cycles that can create potholes. Early spring is usually considered pothole season.

Repairs to potholes is a challenge as crews not only have to fill the hole but they have to seal it to keep water from going into any cracks.

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