The Transportation Safety Board of Canada (TSB) has found a broken rail, due to an undetected defect led to the October 2014 derailment of a Canadian National Railway (CN) freight train near Clair, SK, Canada.
The investigation determined that the train derailed when a sudden and catastrophic failure of one of the rails occurred under the train, due to the presence of an undetected defect. Poor rail surface conditions had masked the presence of this defect and reduced the effectiveness of visual inspections and ultrasonic inspections. Including this occurrence, the TSB has investigated seven occurrences in the past 10 years involving a rail break due to a pre-existing rail defect that was not detected by ultrasonic testing.
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