Concerns were raised over the “bumpier” tracks just one week before a train derailed in east Sussex, an MP has said.
Two people were seriously injured and 18 others hurt after a Southern Rail passenger train travelling from London Victoria to Eastbourne derailed and flipped on its side near Lewes on Thursday afternoon.
James MacCleary, the Lewes MP, said that there had been a meeting with Greater Thameslink railway to discuss the track, which was “possibly a result of the incredibly hot weather”.
Major disruption to services is expected today, as investigators from the Rail Accident Investigation Branch (RAIB) attend the scene.
The RAIB will seek to establish the “root cause” of the incident, which saw three carriages carrying around 150 people leave the railway.
Some passengers described being dragged along the floor, while others said there instinct was to grab loved ones. Images from the scene show people standing on top of overturned train carriages.
The former chairmain of the Strategic Rail Authority said investigators should be able to see “what the track looked like as the train arrived”.
Images shared on social media appear to show a significantly bowed section of the track.
Richard Bowker told BBC Radio 4’s Today Programme the RAIB will “be looking at things like the condition of the track”.
He added: “We’ve seen images of damaged track – was that caused by the derailment, or did it cause it, or a bit of both? They’ll look at the effects of heat.
“The train itself I would expect to be fitted with forward-facing CCTV cameras, so it will be possible to see, I would suspect, what the track looked like as the train arrived.
“They will be able to download data from the train. It has like a black box. They’ll know what speed it was going. They will know if there were any braking applications.”
Mr Bowker said investigators would examine the ground beneath the track and the embankment to determine whether hot weather had caused it to dry out, as well as checking for any conditions specific to the site.
Multiple angles from the Lewes train derailment in Sussex appear to show a significantly bowed section of track beyond the end of the carriages pic.twitter.com/aOzroyUOWq
— Henry Lloyd (@henryjlloyd) August 13, 2026
The former chief executive of Etihad Rail said the incidence of rails buckling in high temperatures “has actually been steadily falling over the last sort of 20-30 years”.
He added: “One of the reasons being that we use slightly heavier rails, we use better fastenings and stuff like that.
“But physics is physics, and one of the challenges we’ve got as we see more extreme ranges of heat is dealing with that.”
Network Rail has said it is too early to say what caused the crash, but the line will remain closed until further notice.
Despite this, John Whitehurst, the interim chief executive officer of Greater Thameslink Railway (GTR), which operates Southern services, has reiterated that these incidents are “rare” and that “the railway is very safe”.
He told BBC Breakfast: "These incidents are rare. We do constant safety checks and put speed restrictions in place, or stop trains where necessary.
"We are working with the Rail Accident Investigation Branch and emergency services. The line will be blocked until this has taken place."
