How are Potholes Formed?

Potholes are the enemy of motorists and cyclists alike. Even pedestrians can end up taking a tumble on one, as they don’t just form on roads – they can occur anywhere, from pavements to car parks.

They’re not just unsightly, they can cause severe damage; cars can burst tyres, bend rims and even damage suspension components by running over potholes, while cyclists can easily buckle their bike’s wheels on the things. According to Kwik Fit’s Pothole Impact Tracker report, potholes dealt vehicles a whopping £1.7bn in damage in 2022 alone.

It’s no secret how damaging potholes can be. But just how are they formed – and why does the UK experience them so frequently? Let’s find out.

How potholes are formed

Here’s a step-by-step overview of how potholes are created.

  1. A fresh, gleaming new road surface is installed.
  2. Over time, wear from vehicles, cyclists and pedestrians using the surface begins to create small cracks in the surface. This is an inevitable consequence of regular use, and can’t be avoided.>
  3. Rain falls and enters these small cracks. This isn’t a problem until the weather turns colder, at which point the rain water freezes.
  4. When it freezes, it expands and hardens, causing the cracks to grow. Then, when the rainwater thaws once again, the cracks are noticeably larger.
  5. As traffic continues to use the road – and rainwater continues to freeze, thaw, freeze and thaw again, the cracks get larger and larger. Eventually, chunks of the road surface break off and, voila, you have a pothole.

Why is the UK so notorious for potholes?

Largely, this is due to our climate. Because we get a lot of rainfall over the winter – and because the temperature fluctuates so much – the rainwater on our roads freezes and thaws an excessive amount. This is too much for any road surface to handle, and potholes are inevitable as a result.

Other factors include a lack of maintenance on the part of local councils (often due to tight resurfacing budgets) and heavy vehicles travelling on roads that weren’t really built for them. Lorries can exacerbate any existing damage and cause new issues, like making the surface uneven. These factors explain why motorways and major A-roads tend to be in much better shape than minor roads.

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