Rail operators have apologised after a report into last Thursday’s derailment in East Sussex found a track defect on the approach to where the train derailed on the hottest day of the year so far.
An interim report by the Rail Accident Investigation Branch (RAIB) said CCTV images showed the “track geometry irregularity” existed before the incident near Lewes injured 30 people.
The watchdog published an image that appeared to show the track had buckled – something that can happen in high temperatures – before the Southern train derailed.
It said its investigation was taking weather conditions into account, as well as the status of the track, embankment, condition of the train and the effectiveness of any measures taken to mitigate the hot temperatures.
The report said there had been “a sustained period of hot and dry weather” and that the ambient air temperature at the time was about 27C, according to the nearest weather station to the site.
In a joint statement, Network Rail and Greater Thameslink Railway (GTR), which runs Southern, said they were “very sorry that this happened on our railway”.
“We also recognise the ongoing impact the incident has had on customers, local communities and railway colleagues,” said Lucy McAuliffe, Sussex route director at Network Rail, and John Whitehurst, chief executive at GTR.
“Safety is and will always remain our highest priority. While Britain’s railway is one of the safest in the world, when incidents like this occur it is essential that we understand exactly what happened and identify any lessons that can be learned.”
The stretch of railway between Lewes and Haywards Heath is scheduled to remain closed until at least the end of service on 26 August. That will give time for the train to be recovered – a complex job involving the derailed carriages being lifted by crane – and for recovery teams to make sure evidence is preserved.
The incident happened on 13 August amid the UK’s fifth heatwave of the summer, during which two trains derailed in less than 24 hours. The second derailment occurred on Friday when the rear carriages of a Greater Anglia train came off the track “in an upright position” at Wickford railway station in Essex, with no reported injuries.
The embankment on which the railway sits near the Lewes derailment site is made of clay, meaning it is “sensitive to variations in water content and may undergo movement as moisture levels change”, the RAIB said.
It added that “although, at this stage, there is no evidence to indicate that a significant embankment slip occurred before the accident, there is evidence that some movement had previously taken place”.
RAIB investigators said they had received “several reports of rough riding” from passengers on other trains in the same location.
It is understood that investigation teams still consider the inquiry to be in its very early days and the final report may not be published for a year or longer.
The Office of Rail and Road (ORR) said it was also “investigating the circumstances of the incident” but declined to comment further. Unlike the RAIB, the ORR’s remit is to look into potential “breaches of health and safety law” and it has the power to prosecute on those grounds.
The train was travelling at about 65mph – within the 70mph speed limit – as it approached the site of the incident, with about 150 people onboard.
Three carriages ended up on their side, trapping passengers and injuring 30 people, including 20 who required hospital treatment, the RAIB said. “Significant damage was caused to the train and to railway infrastructure,” the watchdog added.
James MacCleary, the Liberal Democrat MP for Lewes, said the early findings “raise serious concerns”, and the fault on the track was “deeply concerning”.
“I travel this line very regularly and reported to the authorities just how bumpy this section of track had become. We cannot assume that this is related, but that makes the current findings even more troubling.”
