A train derailment near Lewes on 13 August is currently under active investigation by the Rail Accident Investigation Branch (RAIB). While the cause is not yet confirmed, experts are discussing the potential for extreme heat to have contributed to the incident.
Peter Dearman FREng, a Fellow of the Royal Academy of Engineering, highlighted that lessons from previous investigations, including those following extreme heat events in 2022 and a 2020 derailment, are important. The 2023 Extreme Heat Taskforce report made 47 recommendations covering railway maintenance and infrastructure.
John Lawrence, Chair of the IET Railway Technical Network, suggested that heat expansion in rails causing buckling is a possible issue, especially when compounded by multiple days of hot weather. He also noted that soil moisture deficit, particularly in clay areas, could cause track bed shrinkage and rail distortion.
Professor Phil Blythe of Newcastle University stated that while not yet confirmed, buckled rails related to extreme heat could be a cause. Dr Ioannis Koliousis, Associate Professor of Logistics & Supply Chain Management at Cranfield School of Management, described extreme heat as a credible potential factor, noting that steel rails expand with rising temperatures, creating compressive forces that can lead to buckling if the track cannot restrain them.
Investigators will need to examine various factors, including track geometry, rail stress, ballast, sleepers, fastenings, maintenance records, local temperatures, recent engineering work, and any heat-related speed restrictions. Dr Koliousis cautioned that visible track distortion after an accident does not necessarily mean it caused the derailment, as the derailing train itself could cause substantial track displacement.