The UK’s railways faced unprecedented strain this summer, with two derailments in August linked to extreme heat. Network Rail, the public body managing most of the network, acknowledged the challenges, citing “exceptional” stress on infrastructure from rising temperatures. Traditionally, our railway system hasn’t been designed for hot weather.
So that puts our railway system under stress but also our overhead lines as well.
That can also cause trouble for the whole [railway] system, not just the ground infrastructure,
said Xueyu Geng, a professor of ground engineering at the University of Warwick, explaining how heat-induced expansion can destabilize tracks.
Heat-Related Risks and Railway Vulnerabilities
Steel rails expand in extreme heat, creating compressive stress that can lead to buckling. Most UK tracks use continuously welded rail, which is restrained by sleepers and ballast, making them prone to lateral shifts when temperatures rise. When the rail heats up it wants to get longer but can’t, so it builds up substantial compressive stress instead.
If that stress exceeds the track’s resistance to sideways movement, the track can shift sideways, causing a thermal buckle,
Geng said. We’re expecting the biggest El Niño for over a century, [with Pacific sea temperatures] peaking at something over 3C.
That is unheard of in modern climate records,
said Prof Adam Scaife, the Met Office’s head of long-range forecasting.
Network Rail’s long-range forecast suggests it will be a warm, wet winter – in line with climate change predictions for Britain – and we are doing all we can to be ready for that.
Preparing for an Unprecedented Climate Shift
Network Rail has outlined a £2.6bn programme of works in track maintenance and renewals, including drainage, earthworks, track and overhead power improvements, as well as monitoring and predictive technologies to identify risks earlier and enable proactive intervention. We are continuing to invest in making the railway more resilient to extreme weather and climate change,
a spokesperson said. We need to look at how the hot countries are managing their railway systems,
Geng said, citing examples from Spain, where the rail system is managing between 0C and 45C, and Saudi Arabia, where it is 10C to 55C. The track is pre-stressed.
We need to manufacture the pre-stress level in order to cope [with extreme heat].
In 2015, a freight train derailed near Langton, Lincolnshire, on the hottest day of the year to that point, and an investigation found the track had buckled in the heat. There will need to be a serious look at parts of the network where past decisions have compromised the infrastructure,
said William Powrie, professor of geotechnical engineering at the University of Southampton. He highlighted the Salisbury to Exeter line, where the extensive singling on the Salisbury to Exeter line, and reducing the train speed to account for poor track quality as a result of soil moisture deficit destroys the timetable
.
The immediate priority should be to use the warning time we have,
said Ioannis Koliousis, associate professor at the Cranfield School of Management. Before a potentially wetter and stormier autumn and winter, Network Rail should intensify drainage clearance, culvert inspections, earthwork monitoring and vegetation management, particularly at locations with a known history of weather-related failures.
He stressed that while clearing drains prepares for the next storm, redesigning or increasing the capacity of that drainage system prepares us for the next 30 years. We need to be doing both,
he said.
The Path Forward: Adaptation or Crisis?
Rail operators need to be prepared in the coming year for both potentially prolonged periods of hot dry weather and more intense rainfall and storminess,
said William Powrie. Network Rail’s spokesperson acknowledged the challenges, stating, Britain’s railway is one of the safest in the world and improving its resilience to more frequent and extreme weather is an ongoing priority.
Geng warned that Britain must begin to factor in higher temperatures as part of the design standards for its railways. We need to manufacture the pre-stress level in order to cope [with extreme heat],
she reiterated.
