Trains will run at lower speeds in Lancashire today (July 25) in order to keep passengers safe in the record heat, Network Rail has warned.
Speed restrictions will be put in place on the West Coast Main Line from 12pm until 8pm, affecting services running through Lancaster, Preston and Wigan North Western stations.
Network Rail said it has activated its 'extreme weather response teams' to prepare for disruption across its North West network.
It said speed restrictions will be introduced in areas where tracks are at risk of buckling due to extreme heat, including lines in Lancashire.
The steel used for rails in the UK have a stress-free temperature of 27°C, the average summer rail temperature in the UK.
But UK tracks are not designed to cope with higher temperatures. This means that when steel rails get hot, they expand, which can cause the rails to buckle.
The rail tracks will be under intense stress today as UK temperature records are set to be smashed.
A maximum temperature of 31°C is expected in Lancashire.
As a precaution, Network Rail said trains must run at slower speeds.
James Dean, chief operating officer for North West and Central, said: "Keeping passengers moving is always our top priority. But we want people to be prepared.
"The hot weather creates risks for the railways, as temperatures can rise to more than 50°C on the tracks in direct sunlight.
"The steel used in the rails can quickly become very hot, which can lead to tracks bending and buckling under stress.
"If the soaring temperatures do lead to us having to put in place slower speeds for safety reasons, please bear with us our engineers work to fix the problem.
"It may mean some journeys take longer.
"For those who must travel by rail, we’d remind people to carry some water with them so they don’t get too parched, and always check before travelling so they know exactly what to expect."
The rail operator said passengers should not be overly concerned, but advised that people should 'be prepared'.
Since the last hottest summer in 2003, number of buckled rail incidents has reduced by 83 per cent.
Network Rail said the hot weather can also lead to signal failures, leading to possible delays to services throughout the UK.