Updated

Updated · BBC.com · Aug 14

RAIB Probes Lewes Derailment That Injured 20 as Heat Impact on Tracks Comes Under Scrutiny

Updated

Updated · BBC.com · Aug 14

RAIB Probes Lewes Derailment That Injured 20 as Heat Impact on Tracks Comes Under Scrutiny

Q: If the track was inspected just a day before, what hidden flaw caused a terrifying train derailment hours later?

The hidden flaw has not been confirmed, but investigators are focusing on a possible heat-related track defect — most likely a buckle or loss of track geometry that may not have been visible during the inspection the previous day. Photos from the scene and witness accounts point to distorted track, and Network Rail has said the role of temperatures in the 30s Celsius will be examined. In extreme heat, steel rails can expand sharply; if the stress is not relieved, the track can shift sideways or deform. Track temperature can run far above air temperature, which means conditions can worsen quickly within hours, even after a routine check. That helps explain how a line inspected the day before could still fail later. An inspection may find no obvious defect at that moment, but heat can trigger a rapid change afterward, especially if there is an underlying weakness in the rail, fastenings, ballast, embankment, or joints. Rail specialists also note that hidden failures can develop in the track bed or substructure, affecting alignment without immediate outward signs. The Rail Accident Investigation Branch is now examining the track, train, infrastructure, CCTV, signalling and onboard data to establish whether the derailment began with a buckled rail, another infrastructure defect, or a train-related fault. For now, the most credible working theory is a latent track problem made critical by extreme heat, not a confirmed cause.

3 articles · Updated · BBC.com · Aug 14

20 people were injured, including two seriously, after three carriages of a Southern train carrying about 150 passengers derailed near Lewes on Thursday; police said none of the injuries were life-threatening.
RAIB investigators are examining the train, track, signalling, CCTV and onboard data, while Network Rail said the inquiry will test whether extreme heat affected rails or other infrastructure; no speed restrictions were in place.
Weekend services between London Victoria and Eastbourne have been cancelled because the line between Haywards Heath and Lewes is closed indefinitely, with replacement buses serving some stations.
Eastbourne faces disruption just as the Airbourne air show is expected to draw large crowds, and Southern has told Monday commuters to check for updates before travelling.
The Lewes derailment was followed by another train leaving the tracks near Wickford on Friday, widening scrutiny of rail safety during temperatures in the 30s.