 Only minor injuries were reported, but the slip and the derailed rolling stock blocked the line, preventing services operating until Sunday evening.The accident highlighted a flaw in the design of the pneumatically-operated interior doors in the SW carriages, which stuck in position when the compressed air supply was lost as a result of the locomotive being shut down.Three people were needed to open them by hand, sparking concerns that the carriages could not be evacuated quickly in the event of a fire.