How do potholes form?

Let’s talk about potholes. As Transport Secretary Grant Shapps said: “The plague of potholes is a menace on our roads.” For so long now, motorists have suffered the brunt of potholes across the UK’s roads, leading to not only a very unsmooth ride, but potentially burst tyres, knuckles wheels and cracked alloys.

Even recently the Chancellor said the government’s potholes fund which gave local authorities around £500m a year to fix them was not enough, and has pledged £700m in 2023/24 financial year. All with the aim of lowering the costs of vehicle-maintenance for families and businesses. But with crazy figures like that and an evident problem on the UK’s road, just how do potholes form in the first place? We take a look at the main reasons below and how they combine together to create potholes on the roads today.

Bad Weather – Something the UK knows all about

Whether it’s creating new potholes or exacerbating existing issues, bad weather during the winter months contributes to the issue of potholes and if anything, accelerates how quickly they form rather than creating them.

Firstly with freeze-thaw cycles. During winters, and colder ones than normal, the situation starts when water seeps into the cracks in the UK road surfaces. The freezing then takes place and the water expands, which essentially causes that crack to widen. It’s then that the ice will melt once the temperatures rise. This in turn leaves voids under the road surfaces. The pothole is formed and the traffic – which is common in the UK – causes that surface to collapse.

Heavy rain is also an issue for potholes. When water is not drained from the road’s surface, it goes into the cracks and causes soil under the surface of the road to become saturated, weakening it, causing a collapse where once again, traffic and the sheer weight/volume of it will create or expand potholes.

Another less likely, but still possible formation of potholes, comes from flooding. Like heavy rain, flooding will cause parts of the road to become loose. It simply increases the risk of exploiting existing weaknesses in the road structure. In the UK, rural areas are surrounded by rivers and unfortunately from time to time, these local communities can experience flooding, leading to further complications with the roads in the formation of potholes.

Heavy traffic – Stress of the surface

With a highly congested UK road system and millions of daily users, it’s no wonder the UK has heavy traffic with some notorious roads like the M25 experiencing the worst in the country.

Generally, the main reason for the formation of potholes through heavy traffic comes from wear and tear. Logistically, the UK is a hub for cargo and goods. Heavy vehicles such as lorries use the network and with this there is no doubt they will (and do) exert a huge amount of force onto the roads. This means that over time the asphalt will weaken and deteriorate, which leads to cracks and ultimately the dreaded potholes we all know. And when it comes to Asphalt, Henry Williams & Son are leading asphalt surfacing contractors offering increased tensile strength by combining polymer-modified asphalt with geo-grid applications.

Drainage is also an issue when it comes to heavy traffic and potholes. If the drainage systems on the roads aren’t up to necessary standards, the systems can exacerbate the effects of the above wear and tear and water damage combined. Ultimately the water must drain away properly from the road surface or it will accumulate more damage to the asphalt.

Poor Road Construction – Inadequacy costs

As one of the longest-established highway maintenance contractors in the UK, Henry Williams & Son knows all about the effects of poor road construction. As such, let us explain this element of pothole formation.

Firstly, if the base layers of the road are inadequate, this can be a major contributor to pothole formation. The base layer itself is the foundation that supports the pavement above it. Construction must be solid or the base layer is likely to not support the weight of traffic passing over which in itself is a contributor as discussed earlier. Over time, the pavement will form cracks, deform and cause the pothole to establish itself.

The materials used on our road surfaces also play a key role. Like most things in life, quality prevails and the use of quality materials can affect the durability and shield to subsequent pothole formation. Low quality materials will not be able to withstand the stress of our busy roads, leading to far quicker wear and tear than high quality materials. What’s more, improper compaction can play its part. By compaction we mean the process of minimising the volume of materials by applying pressure to the process. The road must, and we mean must, be compacted well during the construction phase. Not taking this into consideration can mean the surface may shift leading to cracks and potholes as time goes on.

Taking all of the above into consideration, it’s clear that poor road construction practices are the key driver and developer in potholes. More so in how quickly they will form. Industry-leading planning and design will go a long way in reducing the amount of time before potholes form, if at all. After that, heavy traffic will play a huge role along with ultimately nature herself, as in bad weather – which we know all so much about in the UK.

In line with this discussion on potholes, important to this are highway maintenance contractors, which are there to ensure the UK road network is safe and functional. Having explained the types of UK roads, it’s obvious to see that repair work will be prevalent, and as such highway maintenance contractors manage this and traffic during such times ensuring disruptions are minimal. Henry Williams is a highly experienced highway maintenance contractor. For more information about asphalt preservation, asphalt surfacing and surface dressing, and much more. Get in touch with Henry Williams today.