Overview
- An eight‑carriage Southern service derailed about one mile north of Lewes on Thursday 13 August, the rear three vehicles overturned, roughly 150 people were on board and 30 were injured with 20 needing hospital treatment.
- RAIB’s interim work shows forward and rear CCTV from earlier services captured a pre‑existing track geometry irregularity at the accident site and on‑train data indicate the train was travelling about 65 mph when the driver applied the brakes.
- Investigators have recovered OTDR data, CCTV, signalling records and laser surveys and will examine track condition, prior maintenance, embankment stability and the role of sustained hot, dry weather in the fault.
- RAIB released the site to Network Rail to begin a complex recovery that includes crane lifts and road removal of carriages, and Network Rail and Southern say the line between Lewes and Haywards Heath will remain closed until September 1.
- Local MPs have pressed ministers for answers and investment, and RAIB’s full report and any safety recommendations could prompt changes to inspection, maintenance and hot‑weather resilience across the South East network.