The soaring heat has sparked rail delays, with thousands of passengers left stranded.
The delays to services came as the “wrong heat” caused chaos on trains on one of the hottest days of the year. Almost 50 trains were cancelled and dozens more delayed as temperatures soared to 33C on Monday 19th June.
Furious passengers took to social media to vent their frustration as Network Rail imposed speed restrictions as direct sunshine threatened to buckle rails.
More restrictions are expected tomorrow, although it is hoped the hot and cloudy conditions will cause fewer problems.
Greater Anglia said: “We are very sorry. Speed restrictions are in place due to high temperatures. Slower running means we can’t run as many trains.”
Network Rail tweeted: “Very hot weather means some speed restrictions.” Network Rail said: “Rails in direct sunshine can be 20C hotter than air temperature. Rails expand as they get hotter and can start to buckle. Speed restrictions are imposed as slower trains exert lower forces on the track, reducing the chance of buckling.”
Network Rail say that in order to reduce the tracks buckling, engineers adjust the tension in the rails when they get laid so that they expand without buckling.
A spokesman for Network Rail explained: “There are some parts of our railway network that we have to take special care of when the temperature rises. When a rail sits in the sun all day, its temperature will rise and it will get longer. If left unchecked, that rail could buckle in the heat. By putting speed restrictions in place on the most vulnerable parts of our route, we can reduce the stresses on the rails and keep trains moving. We know this can be frustrating for passengers, and we appreciate their patience when this happens.”
Furthermore, when rails are initially installed they are stretched so that they sit comfortably at the average temperatures we get in the UK. When those temperatures rise above normal, some areas – such as places where track has recently been worked on – can be more vulnerable to rail breaks, and speed restrictions are put in place.
Network Rail also have engineers and remote monitors to measure rail temperatures, which warn them when the temperatures get too high.
As a result, trains may be slowed down to reduce the impact on the rails which have expanded and would be at a higher risk of buckling.