How Potholes Form and How They’re Fixed

Written by Ty Pier

December 12, 2019

When you hit one, you know it—that sickening thud, the jarring feeling in your spine, and the sudden urge to check your rims. Potholes happen everywhere there are roads:  they’re not limited to cold climates. They can cause a range of damage to your car. It begs the question: where do they come from and how can they be fixed?

Water, Water Everywhere

Potholes form because water gets under the pavement where it isn’t supposed to go. But water will find a way, through cracks caused by sealant on the asphalt pavement that has worn off or failed, or through cuts in the pavement for utility work, or because of intense weather conditions combined with the wear and tear of heavy traffic. Heat and sun or cold and rain can all damage pavement. Once water gets under the pavement’s surface, it may freeze and expand, causing the pavement to buckle or heave, or the water may loosen and wash away part of the roadbed. Either way, when heavy traffic’s weight rolls over pavement that has been weakened by erosion or expansion, the pavement will sag and eventually fail, forming a pothole.  

An Ounce of Prevention

Why do potholes come back year after year? You’d think after more than half a century of roadbuilding, the authorities responsible for maintaining highways and roads would have learned a thing or two about how to prevent potholes. But knowing how to do it and paying for it are two very different things. All too often, tight budgets and public pressure to get a fix in place quickly may require short term repairs that won’t last, ultimately costing more money as potholes continue to recur.

Frustrating Fix

Adding insult to injury are traffic delays caused by road repair. Weather conditions affect what kind of repair can be done when. The quick fix is usually the “throw and roll,” where crews shovel cold asphalt into the hole, and then roll heavy equipment over the patch. But “throw and roll” is just an emergency band-aid. Crews will have to return when the weather warms up to install a semi-permanent fix, where they restore the road’s underlayment, as well as the edges of the hole, before filling the hole with hot asphalt and leveling it to match the adjoining part of the road.

New, Alternative Repairs

A new method called spray injection is becoming more popular. It costs much less overall and takes less time and manpower. A special sprayer truck called a Pothole Killer can fix a pothole in a few minutes using just one driver. The trucks power out the damaged asphalt, fill the holes with a special emulsion, and seal them in minutes. This method is gaining traction, although it creates controversy, drawing complaints that it damages nearby cars and roadways by powering out old asphalt, and that it’s expensive to lease the trucks or contract for the pothole killing service. 

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