The reason the runway melts, the track deforms in the UK

Extreme temperatures have created challenges for infrastructure and caused disruptions on UK rail lines. Some trains were cancelled, while others slowed down for fear that the tracks could warp.

Airport runways and some roadways also present problems in inclement weather.

"Much of our infrastructure is not built to withstand the current temperatures," said UK Transport Secretary Grant Shapps.

Rail Deformation

Steel rails expand and tend to warp with temperature changes in any climate.

According to British rail operator Network Rail, railways worldwide are designed to operate within a temperature range of 45 degrees Celsius, depending on local climatic conditions. For example, Spain's rail network is designed to operate normally between 0-45 degrees Celsius. For Saudi Arabia, this number is 10-55 degrees Celsius.

Meanwhile, in temperate countries like England, railways are often designed to operate in the normal temperature range of minus 10-30 degrees Celsius. Sleepers and ballast are spread evenly under the tracks. has the role of fixing the track in both winter and summer.

However, when Britain recorded its hottest day ever, with temperatures exceeding 40 degrees Celsius, the actual temperature at the track could reach 60 degrees Celsius, leading to the expansion of steel bars and buckling back.

The actual temperature at the track can reach 60 degrees Celsius causing the steel bars to buckle.

A fast-moving train on rails can accelerate that process through the heat caused by friction. Therefore, in extreme hot weather, trains may face a higher risk due to the phenomenon of steel rails warping.

Against this backdrop, train speed limits were introduced to protect railway lines. At some railway lines, the speed limit is even cut in half.

Power lines above electrified railway lines also expand and sag in hot weather or contract in cold weather. Engineers sought a solution using a pulley system to reduce the impact of this phenomenon. But in the end, power lines still sag if the weather gets too hot, putting them at risk of tangling and entangling the power rods on the roofs of trains.

Asphalt melted

National Highways, the British government-owned company responsible for the operation and maintenance of the roads, said highways and arterial roads were built with improved asphalt surfaces.

In theory, they are hard to melt and can withstand an internal temperature of 60 degrees Celsius or an outside air temperature of 40 degrees Celsius.

However, most of the basic asphalt that is laid on local roads can start to melt at 50 degrees Celsius.

"The road surface becomes slippery and subsides, making it very difficult for vehicles to brake," said Professor Xiangming Zhou, head of the civil engineering and environmental research department at Brunel University (UK).

"Crushed asphalt is cheap, less abrasive to tires than some other materials, but because they are black, they tend to heat up faster in the sun," added Professor Zhou.

This is why UK authorities have asked specialized trucks, often used in icy weather, to be on standby to spread sand and dirt on the asphalt.

About 4% of roads in the UK are made of concrete. Many countries use concrete to build highways because the material is more durable than asphalt. Even so, they are still not immune to problems in extreme temperatures, and the closure of the A14 route is an example.

The two-way street near Cambridge was originally paved with old concrete slabs. Due to the hot weather, the high temperature caused the old concrete slabs to expand and warp, creating protrusions that forced the operator to close and make emergency repairs during the night.

Rick Green, president of the Asphalt Industry Alliance, said that building a road that could withstand all temperatures was 'a challenge for design engineers'. At extreme temperatures, the surface "does not melt, but the bitumen in it can soften", "increasing the risk of deformation".

Damaged airport runway

Luton Airport, north of London, also has an asphalt problem as temperatures soar. The airport had to suspend operations on the afternoon of July 18 after the heat caused a "defect" on the runway, forcing flights to be diverted.

According to the airport, "high surface temperatures caused a small portion (on the runway) to rise" and engineers fixed it within hours, but that still caused major disruption for passengers.

While local roads are often shaded by surrounding trees and buildings, runways are exposed to direct sunlight and are subject to additional thermal stress from aircraft landing and take-off. Regular repairs and maintenance take place.

Heathrow Airport, which is even hotter than Luton, also experienced runway problems last week.

Sky News on July 18 reported that hot weather also melted the tarmac at Brize Norton Air Force Base in Oxfordshire, southeast England. The news agency, citing a military source, said the Royal Air Force had suspended flights in and out of the base.

What is the solution?

Network Rail spends hundreds of millions of pounds a year on mitigating the effects of climate change. However, most of the money is used to combat erosion or storm damage.

Future infrastructure could be engineered to withstand a warmer climate, but then it could be more susceptible to damage and cracking during cold winter weather, when the tracks shrink. Some rail materials, such as concrete sleepers, are designed to withstand a greater range of heat fluctuations but will be significantly more expensive.

In the face of extreme weather, countries will also have to watch to adapt and this is certainly time consuming and costly. Projects to improve roads to better withstand the heat will become an economic and political problem.