Trains have been forced to run more slowly in southern Britain because of the heatwave, with speed restrictions imposed on two main lines out of London as temperatures on the track neared 60C.
Passengers have been urged to check before travelling and warned to expect longer journeys and possible cancellations on routes west from London Paddington and south of the capital on the Brighton mainline.
Restrictions were put in place at the weekend for the Brighton mainline through Monday and Tuesday, affecting Southern, Thameslink and Gatwick Express services.
Network Rail and train operators decided at midday on Monday to extend the speed restrictions to the western mainline, affecting primarily Great Western trains running to the south-west and south Wales.
As temperatures in the south exceeded 30C, steel rails were heating up to about 60C in the hottest parts of the tracks such as deep cuttings and suntraps, according to Network Rail. Other factors such as timber rather than concrete sleepers, and the speed of trains, increase the risk of buckling or failure.
The speed restrictions imposed west of Paddington through the Thames valley area were likely to mean a 10- to 15-minute delay on most trains, according to a GWR spokesperson.
The compounding delays were expected to bring more disruption and cancellations later in the day. Glastonbury returnees mostly avoided further duress: GWR said it had already picked up more than 6,000 festivalgoers from Castle Cary station in Somerset on Monday morning before the speed restrictions started.
With temperatures expected to nudge higher, railway managers confirmed the speed restrictions would stay in place until 10pm on Tuesday night.
The heat has not reached the extremes of three years ago, when services across England and Wales were disrupted and under speed restrictions amid fears that rails would buckle. Network Rail painted critical sections of the railway white this spring to help reduce the impact of heat. The state-owned company is wrestling with the impact of the climate crisis on more than 20,000 miles of track, thousands of signals, stations and level crossings that it owns and maintains.
A spokesperson for Network Rail and the train operators said: “With temperatures set to soar as forecast by the Met Office, speed restrictions have to be imposed across large parts of the network to ensure everyone’s safety.
“We’re sorry but this means we won’t be able to run as many trains as normal and journeys will take longer. Trains that are running will also be much busier. If you are able to work from home, then that may be your best option.
“If you do take the train, then please remember to take a bottle of water, and if you begin to feel unwell, seek help at the next station and speak to station staff. Pulling emergency alarms onboard may delay us getting help to you.”
While passengers in northern England and Scotland have escaped the heat, those hoping to take the west coast mainline north of Carlisle to and from Glasgow were left unable to travel after a tree fell and blocked the line.
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