How Do Weather Conditions Affect Roads?

While British weather is generally mild, any sudden changes in temperature, heavy rainfall, long periods of high heat, snow, fog or ice can cause significant impacts on roads and throughout transport networks.

Roadway designers and highway contractors carry out thorough evaluations when designing road systems, factoring in potential weather fluctuations and extremes to ensure the completed road can withstand all the potential pressures.

The first step is to understand which types of weather cause the greatest impacts and how to ensure highways adapt to regional conditions and are suitably protected from extremes that can cause damage.

Weather Conditions and the Impact on Roads

There are countless types of weather that influence the way highways perform, impacting everything from surface temperatures to pothole formation, flexibility and skid resistance. Of the many weather patterns that can affect roads, these include:

• Heatwaves and hot weather that cause road surfaces to expand, soften and melt.
• Heavy rainfall resulting in flooding, surface deviations, cracks and potholes.
• Snow, frost and ice exacerbate wear and tear on older roadways, where freezing and thawing can turn a small crack into a large chasm.

When weather forecasts indicate longer periods of rain and snow, drivers may be cautioned to travel only if essential. Still, it is impossible to completely mitigate the flow of traffic on central transport links and motorways.

Therefore, highways contractors conduct ongoing research, testing and analyses to determine the materials, design approaches, techniques and methods that will ensure roads remain usable and safe even in the worst weather conditions.

What Happens to Roads During Heavy Rain?

Rain is an inevitable aspect of living in the UK, but where rain is unusually heavy or continues day after day for several weeks, it can mean that surface imperfections caused by tyre friction become dramatically larger.

In drier conditions, small cracks slowly expand over time, but where rainfall is continuous, it seeps into the cracks and can widen the width and depth of deviations.

During the winter, the impact is even more rapid, where water runs into cracks and crevices and freezes, forcing the materials further apart before thawing and leaving large gaps that require urgent reparative maintenance.

Rainfall and reduced carriageway conditions can also affect the friction of the asphalt, and therefore stopping times, visibility at distances, and cause potential obstructions within lanes.

How Does Snow Damage Road Surfacing?

The immediate issue during snowfall is that ice and freezing fog affect visibility conditions and mean the decreased tyre adhesion to the road can mean cars skid, crash, or lose sufficient traction to brake within safe distances.

Salt and grit can help to improve the conditions for tyres, but the resultant deterioration can be serious, where like rainfall, the snow seeps into cracks and freezes. The expansion of freezing water makes a small crack much bigger and causes weakness across the surrounding surface, leading to potholes.

Summer Heatwaves and Highways

In the warmest summer weather, exposure to direct sunlight and elevated temperatures means asphalt slowly begins to soften and melt. In the worst scenarios, roads can melt under extreme heat to become sticky, tacky, and very difficult to drive on, with resultant damage to vehicles and tyres.

The best approach to damage caused by elevated heat is to repair deviations quickly since buckling and rutting can spread outwards, increasing the volume of the road affected and crossing over into oncoming lanes.

Weatherproofing Roads Against Heavy Rainfall

Preservative treatments and intelligent highway design can provide protection against conditions such as prolonged rainfall, reducing the risks of aquaplaning and surface condition faults before hazardous cracks and potholes develop.

Waterproofing surface treatments can prevent excessive water ingress, which is a primary cause of potholes and surface issues, using specifically engineered preservatives for use in highway design. 

Emulsions can be in the form of a surface dressing sealed with a bitumen emulsion with fast curing times and comprehensive protection from the elements. 

Preventing Cold Weather Damage to Roads 

The cycle of rainfall, sub-zero temperatures, freezing water, and thawing is one of the most common causes of roadway damage in the UK, where flexible asphalt becomes more brittle when the climate turns cold.

Crack formation is, unfortunately, a natural outcome of continual pressure, friction and traffic on any highway, and contractors incorporate varied techniques and treatments in roadway design to enhance longevity and durability to reduce water ingress damage.

However, cracks that form naturally can expand substantially when water seeps into deviations, and icy weather causes expansion that turns a slim crack into a larger deviation, normally developing into a pothole if not swiftly addressed.

Some of the available strategies include setting roadway surfacing at an angle to improve water run-off and redirecting rainfall into gutters and drainage systems to reduce the volume of rain that accumulates on the roadway surface – also important to avoid safety risks such as aquaplaning.

More often, and where roadway angling is unsuitable, highways can be designed with high-performance drainage, sealant treatments, and proactive maintenance to seal cracks, repair potholes and add grit to enhance surface friction when snow and ice are forecast.

Designing Modern Roadways to Withstand Extreme Weather

There are many ways to improve the way roads stand up to extreme weather, be that heat, snow, ice, rain, or fog. Material selection is a pivotal aspect where combining aggregate grades with asphalt provides enhanced resistance to flooding.

Other options, such as polymer-modified binders, reduced the vulnerability of roadways to increased asphalt temperature, reinforcing the structural capacity of asphalt and enhancing resistance to warmer climates. Modified binders are both sustainable and resistant and can maximise performance, primarily when applied as a sprayed sealant.

While extreme weather conditions are infrequent, a lack of preparedness can be detrimental, but a rapid response to road surface degradation can be essential to correcting faults, reinforcing the structural stability of the roadway and leaving it in a good condition to cope with repeat weather patterns or recurring seasonal conditions.

For more information about the ways UK weather conditions can impact road performance and opportunities to mitigate impacts and extend the lifespan of roadways and surfacing, please contact Henry Williams & Son at your convenience.