Undetected Rail Flaw Led to October 2023 CN Derailment
Written by David C. Lester, Editor & Jennifer McLawhorn, Managing Editor
Site of the October 2023 derailment.
Courtesy of TSB
DARTMOUTH, Nova Scotia - The Transportation Safety Board of Canada (TSB) has released an investigation report into the 2023 derailment near Dunsinane, New Brunswick.
According to the report, from the Transportation Safety Board of Canada (TSB), a CN freight train was traveling on the Sussex Subdivision on October 30, 2023 when at least four cars had derailed. The report states that after a “train-initiated emergency application occurred,” the conductor then completed an inspection where they found the derailed cars, and “approximately 2000 liters of methanol” leaking from one of said cars.
The TSB states that its investigation found that the cars derailed after traveling over a small bridge, and that the north rail broke as a “result of an internal fatigue defect likely originated from fine cracks in the surface of the rail, known as head checking.” Records show that this rail section had already been tested with third-party ultrasonic rail flaw detection with a hi-rail vehicle three times in five months prior to the derailment. According to the report, the tests were each “unable to obtain valid results.” When the operator used a hand tool, it did not identify a defects internally.
The report adds that “According to CN records, the last rail grinding program for the Sussex Subdivision was completed on 18 June 2023, approximately 4 months before the derailment. However, due to the risk of fire, grinding on the bridge at Mile 32.7 had not been completed and nor had it been rescheduled prior to the occurrence.
The investigation showed that if rail surface conditions that affect the ultrasonic RFD testing reliability are “not required to be reported to a railway operator, internal rail defects can remain undetected and mitigation measures may not be implemented, increasing the risk of a derailment due to an in-service rail failure.”
Derailment Site, Courtesy of TSB
Recovered broken rail with head checking (Source: TSB)
North rail from the roadbed approaching the bridge showing grinding marks, circled in yellow (Source: TSB)
