Train companies across much of England are advising passengers that the heatwave will affect train services and could lead to delays and short-notice cancellations.
The Met Office has issued a rare red extreme heat warning for Wednesday 24th and Thursday 25th June, with forecasters warning that June’s all-time temperature record could be broken. However, high temperatures are expected on Tuesday afternoon as well, so the rail industry is advising people to check for information before travelling for the rest of this week.
For Londoners, Transport for London (TfL) is warning that London Overground and Elizabeth line services are likely to be most affected by the heatwave.
The problem is that extreme temperatures can affect railway infrastructure, requiring trains to run more slowly to keep services operating safely. In addition to a reduced timetable, some trains may operate at reduced speeds.
The cause is that the long railway tracks expand in the high heat, and while they are designed to expand a bit, the heatwave is far outside the temperature range they are meant to operate within. All railways around the world are designed for average temperatures for the region they are built for, but exceptional temperatures can’t be designed out, no matter which country you live in.
It would be possible to install railways to cope with higher temperatures, and when installing steel rails, Network Rail uses a process called ‘stressing’ to protect against buckling. This sets the temperature range the track can comfortably cope with. Stressing rails to cope with higher summer temperatures would however then mean they are less resilient to low temperatures during winter. So it’s a balancing act and generally works, except during the sort of rare heatwave we’re having at the moment.
Apart from the tracks, high temperatures can cause overhead power lines to sag, slowing trains due to unreliable electricity supply and the risk of the train’s pantograph getting caught in the sagging wires.
To help passengers change journeys if possible, some ticket restrictions have been lifted to offer more flexibility. Passengers should check with the train operator for details.
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