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  • Writer's pictureSafer Highways

How bacteria and self-healing roads could soon fix the UK’s 750,000 potholes

As the world grapples with the accelerating pace of climate change, the UK's expansive network of roads, stretching over 250,000 miles, is increasingly vulnerable to the damaging effects of extreme weather.

From melting tarmac during intense heatwaves to the proliferation of potholes due to repeated freeze-thaw cycles, the challenges facing the UK road infrastructure are growing in both scale and complexity.

A recent survey conducted by climate change group Round Our Way has shed light on the severity of the situation. The survey revealed that 60 per cent of local authorities reported a staggering total of 750,000 potholes across the UK in the year 2023 alone. Surrey County Council topped the list with an alarming count of 68,000 potholes.

The economic cost is substantial, as reflected in the UK government's decision to divert £8.3 billion from the HS2 extension project to local road repairs in November 2023.

However, the Asphalt Industry Alliance estimates that a comprehensive solution to the UK's pothole problem over the next decade would carry a hefty price tag of £14 billion.

As a result, there is an urgent call for research into innovative solutions that can adapt to climate change and contribute to the net-zero emissions goal.

How do potholes form?

Understanding the science behind pothole formation and the potential impact of climate change on our roads is the first step towards a solution.

Potholes are primarily the result of three compounding factors: water, traffic, and freeze-thaw cycles. As vehicles traverse the roads, they exert pressure on the surface, causing small cracks to form and then gradually expand. These cracks allow water to seep into the surface, accelerating its deterioration. The freeze-thaw cycle, where water within the road freezes, expands, and subsequently thaws, further weakens the surface, eventually leading to the formation of potholes.

Climate change, with its associated increase in extreme weather conditions, is set to exacerbate this issue. The UK has been experiencing more intense and frequent rainfall events in recent years, resulting in more water infiltrating into the roads.

Furthermore, the fluctuating extremes of summer heat and winter cold increase the number of freeze-thaw cycles, accelerating the rate of pothole formation.

What innovative technologies could help us fix the problem?

We need innovative and sustainable solutions to address these challenges, such as robust, eco-friendly road materials. And they exist.

For example, self-healing asphalt, a ground-breaking material infused with steel fibres and epoxy capsules can repair small cracks and prevent water infiltration. This is done by applying heat to the steel fibres using an induction machine, which then causes the mortar with the asphalt to melt and repair itself.

Another potential solution is incorporating bacteria into cement-based road materials to create self-healing roads. The bacteria, usually contained within tiny capsules, are mixed

into the cement used for road construction.

When a crack appears on the road surface, these capsules break open, releasing the bacteria. These bacteria then begin to produce calcite, a form of limestone, as a by-product of their metabolic process. The calcite fills in the cracks, effectively healing the road. This not only extends the lifespan of roads but also reduces the cost of regular maintenance work.

Also rather promising is the use of graphene-reinforced asphalt. Graphene, a one-atom-thick layer of carbon atoms, is renowned for its exceptional strength and flexibility. When incorporated into asphalt, it significantly enhances the material’s resistance to wear and tear, making it less susceptible to cracking and pothole formation.

As well as new materials, innovative technologies can also play a pivotal role in improving road resilience. Ground-source heating and cooling systems, for example, can help to regulate road temperatures and lessen damage.

In winter, these systems can prevent ice from forming on the road surface, reducing the risk of accidents and the need for salt and grit treatments. During the summer, they can maintain a cooler road surface, preventing asphalt from softening and deforming due to high temperatures.

While the initial investment for these technologies may be substantial, the long-term benefits of reduced maintenance costs and increased safety make them a worthwhile consideration. However, adopting these innovative solutions needs to be part of a broader climate change mitigation strategy.

Reducing greenhouse gas emissions, transitioning to renewable energy sources, and promoting sustainable transport options such as public transport, cycling, and electric vehicles are all crucial steps towards a more resilient and sustainable future for UK roads.

While the escalating severity and frequency of extreme weather events due to climate change pose a significant threat to the UK’s road network, by harnessing innovative materials, technologies, and mitigation strategies, we can build a more resilient and sustainable road infrastructure for the future.

The time to invest in these solutions is now, as the consequences of inaction will only become more severe and costly in the years to come.

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