How are potholes formed?

By Christina Bengston
How are potholes like this formed?
Potholes are a menace to cyclists and drivers alike, and the UK's roads are covered in them, but why do they happen and how can they be prevented?

Take action: Fill That Hole

Most potholes are caused by water which seeps into existing small cracks in the surface of the road caused by the wear and tear of traffic and deterioration over time.

Cold weather then causes this water to freeze (and expand) and when this water melts and evaporates in the warmer weather, it creates gaps which then get broken down by the motor traffic.  

How can potholes be prevented?

  1. Inspect surfaces regularly

    A good programme of inspection, supported by reporting tools like Fill That Hole can help councils determine priority areas for repair.
  2. Keep roads well drained 

    Clear ditches, culverts and drains regularly and engineer roads to be clear of standing water. 
  3. Ensure surfaces are watertight 

    Sealing roads with a thin layer of asphalt to ensure it remains watertight and regular maintenance can prolong the life of the road.
  4. Minimise utility works and check quality of repair 

    Road works are often blamed for causing delays and congestion. They also lead to potholes forming as the opening of the road weakens the structure. Local authorities must check the quality of the reinstated carriageway to ensure that the utility company’s contractor has done a decent job.
  5. Regularly resurface 

    All roads will fail eventually. It is often much more expensive continually to repair a failing road than to undertake a full resurfacing.
  6. Reduce traffic 

    The volume of traffic, particularly heavy vehicles, is the main cause of initial road surface failure. Restricting the use of large vehicles on minor roads can ensure that they stay in better condition for longer.

How can I report a pothole?

Download the Fill that Hole app onto your mobile via Google Play or Apple App store (you can also use it in a web browser).

When you see a pothole open the app: 

  • Take a photo of the pothole
  • Enter the location
  • Measure the pothole (give rough estimates if you don't have a measuring tool)
  • Send the report.

Take action: Fill That Hole

Fill That Hole Campaigner and activist Road cycling

Fill That Hole

Potholes are more than a nuisance – they can be a serious danger to cyclists and others. In the UK, there’s an average of one road defect for every 110 metres of road.

Local councils have a duty to maintain the roads, but they can only fill a pothole if they know about it. We set up Fill That Hole to help the public easily report potholes and road defects wherever you find them.

Fill that hole logo in association with cycle sos logo

The updated Fill That Hole tool was made possible by funding and support from law firm Fletchers Cycle SOS.

Further reading