Train derailment probe focusing on hot weather as track appears to have buckled

A train derailment in Lewes, East Sussex, that injured 30 people was reportedly triggered by a buckled track on what has been the UK's hottest day so far in 2026. The Rail Accident Investigation Branch (RAIB) said it will examine weather conditions in its investigation into the crash, which occurred on August 13.

CCTV footage released by investigators shows the deformed track where the incident took place. The fault, identified by cameras on previous services, is classified as a "track geometry irregularity." August 13 saw temperatures soar to 38.1C in west London, with "a sustained period of hot and dry weather" preceding the accident, the RAIB noted.

Passengers on other trains at the same location reported experiencing "rough riding" after the derailment. Preliminary analysis of the derailed Southern train's onboard data recorder indicates the train was traveling at around 65mph as it approached the derailment point at 3:54pm on August 13. Of the 150 people onboard an eight-carriage service from London Victoria to Eastbourne, three carriages ended up on their sides, trapping passengers. Thirty individuals were injured, including 20 who required hospital treatment.

Network Rail's Sussex route director, Lucy McAuliffe, and GTR chief executive John Whitehurst issued a joint statement emphasizing that Britain's railway is "one of the safest in the world" and stressing the importance of understanding what happened at Lewes to identify lessons. They committed to carefully considering any recommendations from the investigation and working across the industry to implement them.

The railway between Lewes and Haywards Heath remains closed until at least the end of service on August 26 for recovery and track repair. Liberal Democrat MP for Lewes, James MacCleary, expressed serious concerns about the preliminary findings, citing a pre-existing irregularity on the track as deeply worrying. He highlighted his previous reports about the bumpy nature of the section and called for an investigation into chronic underinvestment in rail infrastructure in the South East.

A Department for Transport spokesperson reiterated that safety remains the top priority and pledged to ensure the railway industry acts on the findings of the RAIB's full report. The UK's railways are among the safest globally, with delays caused by track faults falling by 45% since the late 2000s. The UK government has invested £29 billion to renew and maintain the network and an additional £2.6 billion to improve climate resilience. Another train derailed a day after the Lewes incident, with no reported injuries.