Why UK Roads Get Hit with Potholes in Winter?

As Civil Engineers and surfacing specialists we at Glenco Civil Engineers get the above question asked allot and specially nowadays when the weather is changing. Every winter, roads across the United Kingdom face a seasonal menace: potholes. While potholes can appear year-round, their numbers and severity spike as temperatures drop, particularly in high-traffic areas. But what exactly causes this? and why are UK roads so vulnerable during winter?
1. The Freeze-Thaw Cycle: Nature’s Pothole Maker
The UK’s climate—marked by frequent rain and fluctuating winter temperatures—makes it an ideal breeding ground for this freeze-thaw process. Roads that may have small cracks or slightly weakened areas become particularly vulnerable, leading to an increase in potholes as the freeze-thaw cycle plays out over the winter months.
2. Increased Moisture from Rain and Snow
The UK’s famously wet winters add another layer to the problem. Rain, sleet, and snow mean that UK roads are constantly exposed to moisture. With nearly 150 days of rain per year on average, water is almost always present on the roads in winter, seeping into cracks and laying the groundwork for future potholes. Snow and ice can worsen this effect by melting and refreezing in cycles that speed up pothole formation.
3. Heavy Traffic Strains and Weakens Roads
The heavy volume of traffic on UK roads, particularly on motorways and city streets, is another significant factor in pothole formation. Larger vehicles like buses, trucks, and delivery lorries place additional stress on the road surface. As these vehicles pass over areas where water has weakened the asphalt, the added weight and pressure can lead to a quick deterioration of the road surface.
4. De-icing Salt and Its Impact
To keep roads safe, local authorities spread de-icing salts to prevent slippery surfaces. However, road salt can accelerate the deterioration of asphalt. As salt melts snow and ice, it forms a saline solution that can penetrate the asphalt’s pores. Over time, salt can degrade the binding agents in asphalt, causing it to crack and erode more easily.
In winter, this creates a perfect storm: roads become both more porous and more susceptible to freeze-thaw damage.
Long-Term Solutions to Winter Potholes
Addressing the pothole problem requires proactive measures to strengthen the roads before winter arrives. Here is what Glenco Civil Engineers would recommend:
1. Timely Repairs and Resurfacing
Repairing minor cracks and fractures early can prevent them from developing into full-fledged potholes. Regular inspections and maintenance of high-traffic roads help identify problem areas before the freeze-thaw cycle can worsen them. Resurfacing solutions, such as high-quality tarmac or asphalt overlays, add a fresh protective layer to roads, giving them added durability during winter months
2. Quality Materials
Using high-grade asphalt with better water-resistant properties can go a long way in slowing down the formation of potholes. Modified asphalts that are more resistant to moisture and freezing temperatures are a valuable investment, particularly in climates like the UK’s.
3. Improved Drainage
Ensuring proper drainage systems along roadways can prevent water from pooling on the surface, reducing the amount that seeps into cracks. This is a key factor in mitigating the impact of the freeze-thaw cycle. In areas with high traffic and frequent winter weather, designing better drainage solutions can make a substantial difference.
So, the next time you spot a pothole on a cold, rainy day, remember that it’s the result of natural cycles and traffic pressures. It also serves as a reminder of why regular road surfacing, tarmacking, and proper drainage are essential investments in our infrastructure.