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Lewes derailment track defect before incident

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The gist

Investigators found a track defect before a Lewes derailment injured 30. The cause may be heat-buckled rails on a hot day.

Background

On August 13, 2026, a Southern Rail train derailed near Lewes, East Sussex, injuring 30 people, two seriously. The Rail Accident Investigation Branch (RAIB) has released an interim report finding a 'track geometry irregularity' on the approach to the derailment point, with images suggesting possible heat-buckled track. The incident occurred during a period of hot weather, and the investigation is considering the role of temperature.

How it unfolded

  1. Aug 13, 2026A Southern Rail train from Haywards Heath to Lewes derailed, with three carriages sliding down an embankment. About 150 people were on board; 30 were injured, two seriously.
  2. Aug 14, 2026A Greater Anglia train derailed in Wickford, Essex, in a separate incident. A landslip also disrupted services between Polegate and Eastbourne.
  3. Aug 19, 2026RAIB publishes interim report revealing a track defect existed before the Lewes derailment, based on CCTV from preceding services. Images suggest possible heat-buckled track.

Who’s saying what

Official
RAIB says its investigation will consider the weather as a factor, given the track irregularity and hot conditions.
Operator
Network Rail and Southern owner GTR apologised after investigators revealed the possible heat-buckled track.

Still unverified

The exact cause of the track defect is not yet confirmed; heat buckling is a possibility under investigation.

Sources

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