Climate change is posing an increasing number of challenges, including on European railways. The International Union of Railways (UIC) has launched the Resilient Rail (RERA) initiative to guide infrastructure managers in being ready to deal with heavy rains and high temperatures.
“Extreme heat can cause tracks to expand and buckle”, the report, labelled RERA Temp project, underlined. In order to improve the way such situations are handled in Europe, UIC compiled a document with guidelines on how to tackle these issues and an overview of their impact on the railways.
Just like it did for heavy rains, UIC set out a methodology to identify, prevent and address issues caused by exposure to extremely high temperatures. The methodology is divided in three sections: data preparation and analysis; vulnerability and risk assessment; implementation and monitoring of adaptation measures.
The first one focusses on collecting and analysing climate data and the creation of temperature maps. The second one leads to the prioritisation of assets based on temperature maps, while the last one revolves around the implementation of measures to counter and prevent heat impact on the railways.
Impact of heat on assets
Extremely high temperatures can have a negative impact on various components of the railway infrastructure. UIC pointed out that these assets include tracks, rolling stock, power and signalling systems, communication and control systems, bridges, earthworks and vegetation. As a general consequence, extremely high temperatures require more frequent maintenance and inspections.
Specifically for rail tracks, the main consequences of extreme heat are thermal expansion, loosening of fastenings, cracking at welds and loss of stability. All of these factors can compromise the track geometry, possibly leading to derailments and accidents. Moreover, extreme heat can affect workers’ health and increase their fatigue levels.
Another common phenomenon is track buckling, according to the UIC document. This a phenomenon involving “a significant lateral displacement of the track that leads to an unstable equilibrium condition”. This occurs when rails are above the so-called stress-free temperature.
Impact on rolling stock
Concerning rolling stock, extreme heat can cause damages to the power supply for both electric and diesel locomotives. Additionally, brake pads and discs on both locomotives and wagons can overheat and expand if too exposed, which could cause warping and reduce braking efficiency, UIC argued. Another consequence of high heat on rolling stock regards the electronics, which might crash or cause short circuits.
Some of the solutions proposed by UIC to tackle high heat on rolling stock include solar heat reflective coating, athermal films and interior insulating foam, which both limit heat penetration. Moreover, they suggested the deployment of enhanced electronic cooling and smart monitoring systems.
Signalling, communication and control systems
Extreme heat also affects railway signalling systems. Conductors expand, causing wires to sag. Electronic components are also more prone to malfunction under very high temperatures, possibly failing to detect trains. For communication and control systems the issues are similar, with their possible overheating and consequent malfunction. This could hinder communication between workers leading to delays and cancellations.
Bridges and environment
For bridges and other structures, overheating can affect joints, bearings, steel components and foundations. Extremely high temperatures also impact the ground where the rail tracks are laying. Longer hot periods can lead to excessive soil drying, which might compromise the stability of the infrastructure. Similarly, extreme heat can affect the vegetation around the tracks, which often provide support along slopey tracks.
The human factor
Another important aspect concerning the impact of high temperatures is how it affects the human factors. Prolonged exposure can lead to skin cancer, heatstrokes and higher stress levels, as well as decreased focus and alertness, UIC stated. This compromises the workers’ health and can more easily lead to mistakes and errors. The document states that almost all positions in the rail industry involve a risk, either when it comes to exposure or sensitivity.