Network Rail has outlined its strategy for tackling the impact of high summer temperatures on the UK's railway network, which includes painting sections of track white. This seemingly unusual practice is a crucial preventative measure designed to reflect sunlight and significantly reduce the temperature of the steel rails, thereby minimising the risk of heat-related disruption.
During periods of hot weather, direct sunlight can cause unpainted rails to heat up to temperatures as much as 50°C higher than the ambient air temperature. For instance, on a day when the air temperature reaches 25°C, the surface of the rail could soar to 75°C. Steel rails are engineered to expand in heat and contract in cold. However, when temperatures become excessively high, the rails can expand beyond their design limits, leading to a phenomenon known as 'buckling', where the track bends or kinks.
Buckled tracks pose a significant safety risk and necessitate the implementation of speed restrictions or, in severe cases, temporary line closures. These measures, while essential for safety, inevitably lead to delays and disruption for passengers and freight services. The white paint acts as a reflective barrier, effectively bouncing sunlight away from the steel and preventing the extreme heat absorption that can cause rails to warp.
Initial trials and ongoing use have demonstrated that applying white paint can reduce rail temperatures by between 5°C and 10°C. This reduction is often enough to prevent the rails from reaching critical temperatures where buckling becomes a significant concern. Network Rail continuously monitors approximately 12,000 miles of track for temperature-related issues, deploying teams to paint tracks in vulnerable areas as summer approaches and throughout hotter periods.
This proactive approach is part of a wider strategy by Network Rail to enhance the resilience of the railway infrastructure against increasingly frequent extreme weather events. Beyond painting, other measures include improved drainage systems to cope with heavy rainfall and vegetation management to prevent leaves from causing issues in autumn. The aim is to ensure the network remains as reliable as possible, regardless of the challenging weather conditions.