Britain's railways have encountered a series of heat-related issues this summer, which has been described as one of the hottest and driest on record. This period has seen a derailment near Lewes, East Sussex, two weeks ago, resulting in 30 injuries. The following day, the rear carriages of a Greater Anglia train derailed at Wickford railway station in Essex, though no injuries were reported.
Network Rail has acknowledged that the summer has "presented exceptional challenges to the railway." The problems have occurred during a period with multiple heatwaves and a declared drought across large areas of England and Wales. Railways in Britain, originally constructed for a cooler, wetter climate, have been under pressure.
Steel tracks expand when hot, and if there is insufficient room for movement, they can generate compressive stresses, potentially leading to buckling. Professor William Powrie of the University of Southampton noted that buckling is a classic concern for railways in hot weather. The soil beneath sleepers and ballast, which helps keep tracks in place, can shrink when dry after long periods of heat and drought, weakening the foundation.
To mitigate buckling, engineers pre-stress rails. In the UK, rails are stretched to avoid compression until the air temperature exceeds 27C. This figure aims to protect against buckling in summer and breaking under tension in winter. Other countries, such as parts of Australia, the US, and southern Europe, set higher stress-free air temperatures.
Simpler measures are also in use, such as painting sections of track white to reduce heat absorption. Network Rail reports that white-painted rails are typically 5-10C cooler. The Network Rail taskforce, established after the 2022 heatwave, found that fewer than half of track buckles recorded that year were identified beforehand.