Rail passengers across the UK are experiencing widespread disruption, with numerous services cancelled or significantly delayed, as a rare red weather warning takes hold across parts of England and Wales. Major operators such as Great Western Railway, Avanti, and LNER have advised against all but essential travel, with over 11% of services across Britain affected by Wednesday morning. This comes as a 'heat-dome' settles over western Europe, pushing temperatures towards 40C in some areas.
Network Rail highlights that hot weather presents challenges as severe as freezing winters for the rail infrastructure. The core issue lies with the steel tracks, which absorb heat and can become up to 20C hotter than the ambient air temperature. While most of the network can operate with track temperatures up to 46C (equivalent to an air temperature of approximately 30C), rails have been recorded at temperatures as high as 51C. As steel expands when heated, the tracks lengthen. If there isn't sufficient room for this expansion, the rails can buckle, leading to a structural distortion where they warp or bend. This necessitates line closures for safety, as buckled tracks pose a significant derailment risk.
Beyond the tracks, overhead power lines, which energise around 44% of UK passenger trains, are also vulnerable to extreme heat. These lines can expand and sag, increasing the risk of them catching on train pantographs, which collect power from the lines. This can bring train movements to a halt or force lengthy reroutes. To mitigate these risks, temporary speed restrictions are imposed across the network. While these restrictions contribute to delays, they are crucial for reducing the forces on the tracks and minimising the potential for buckling and other heat-related infrastructure failures.
John Lawrence, chair of the Institution of Engineering and Technology Railway Technical Network, further explains that the combination of ambient temperature and solar gain significantly elevates temperatures at track level and within trackside equipment. He also points to 'hidden failures' caused by heat stress, affecting vital components such as signalling control, power supplies, and trackside telecommunications. Additionally, lineside fires, potentially sparked by anything from discarded litter to passing trains, can exacerbate disruption.
Efforts to combat the impact of heat include painting tracks white, a measure that can reduce track temperatures by up to 5C, and lubricating rail joints to facilitate expansion. Several operators are also employing advanced monitoring techniques, such as temperature sensors on rails and thermal imaging drones and helicopters, to detect overheating equipment and carry out necessary repairs overnight. Despite ongoing investment and improvements, engineers remain highly concerned about track buckles and dewirements during periods of extreme heat.
The Met Office has issued rare red weather warnings for extreme heat across parts of England and Wales, with amber warnings covering broader areas of England, Wales, and parts of Scotland. Northern Ireland is currently under a yellow warning. Temperatures are forecast to remain exceptionally high throughout the week, with potential record-breaking figures. The public is advised to stay hydrated, avoid direct sun exposure, and check on vulnerable individuals.
Source: Network Rail, Institution of Engineering and Technology Railway Technical Network, Office for Rail and Road, Met Office