The British railway network experienced multiple heat-related incidents during an exceptionally hot and dry summer, including derailments near Lewes in East Sussex and at Wickford in Essex that resulted in injuries and service disruptions. Network Rail characterized the season as presenting “exceptional challenges” to the rail infrastructure, which was originally designed for cooler and wetter climatic conditions.
Railway tracks expand when exposed to high temperatures due to the thermal properties of steel. Modern railways use continuously welded rail sections with limited allowance for movement, which can generate compressive stresses as the metal expands. When these stresses accumulate without adequate space for expansion, the track risks buckling—a potentially dangerous structural failure. Additionally, prolonged heat and drought conditions can dry the soil beneath track foundations, causing it to shrink and settle unevenly, which compounds structural problems. Rail temperatures have been recorded reaching 51C, exceeding the network’s standard operating threshold of 46C. Historical data from 2022 demonstrated the severity of such events, with two days of record temperatures leading to nearly 7,700 cancelled trains and approximately £30 million in estimated costs.
Railways in hotter climates employ different engineering approaches to manage thermal stress. Engineers in countries like Australia and parts of the United States set higher “stress-free temperatures”—the baseline temperature at which rails are designed—allowing for greater heat tolerance. Southern European nations similarly design their rails for higher temperatures since winter conditions rarely pose the risk of rail fracturing. Network Rail has ruled out seasonal re-stressing of British rails as impractical and cost-ineffective given the UK’s variable climate. Concrete slab track, used in some countries as an alternative to traditional sleeper-and-ballast foundations, costs approximately four times more to install.
Potential solutions under discussion include incrementally raising the stress-free temperature standard from the current 27C to 30C on well-maintained modern track sections, though this approach increases vulnerability during cold snaps. Some sections of track are already being painted white to reduce heat absorption by 5-10C. Experts note that more comprehensive monitoring systems are needed, as fewer than half of track buckles recorded in 2022 were identified before occurrence. While modern trains generate substantial sensor data regarding vibrations and rough riding, processing this information at scale remains challenging and currently relies significantly on human detection and reporting by train operators.
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