Transportation Safety Board of Canada report identifies axle fatigue as cause to 2018 derailment near New Hazelton

The Transportation Safety Board of Canada report into a January 2018
derailment near New Hazelton was released today
(map from TSB of C report)

The federal agency tasked with investigation transportation related incidents in Canada has released its findings into a derailment along the CN Rail mainline near New Hazelton in the winter of 2018.

The report into what was described as a Class 3 occurrence was released this morning on the Transportation Safety Board of Canada website, following an extensive review of the background to the train initiated emergency brake application on the Bulkley Subdivision.

The initial inspection at the time of the incident determined that 27 of the 199 car train carrying coal had derailed, listed as the 50th to 76th cars of the westbound train destined for Ridley Terminals in Prince Rupert. 

As a result of the derailment, approximately 2900 tons of thermal coal was released from 24 of the derailed gondola cars.

Most of the coal remained on the railway right-of-way. The estimated total volume of coal recovered was 2800 tons or 97% of the coal spilled. A small amount of coal was spilled into Mission Creek

(Images above from the TSB of C report)

As part of the investigation, the broken axle from the car was recovered and sent to the TSB Engineering Laboratory for metallurgical examination and failure analysis.

From that examination it was determined, that the axle had fractured between the L1 bearing seal wear ring and the backing ring, at the location where the axle journal merges into the fillet. 

As a result, the journal (with the bearing) separated from the rest of the assembly (Figure 6). The fracture was due to fatigue cracking in the journal near the fillet. Crack arrest lines (beach marks) were present on the relatively smooth areas of the fracture surface (Figure 7).

(Images above from the TSB of C report)

While the transportation board notes that it is likely that the axle had been subject to abnormal cyclic loading, the exact cause of the fatigue cracking in the axle could not be determined.

The report also notes that Over the previous 10-year period (2008–2017), there were 23 derailments on CN and Canadian Pacific Railway track caused by a broken axle. In 9 of these derailments (39%), the axle had failed near the journal fillet radius which is part of the axle assembly.

The TSB previously investigated 3 other derailments involving axle failures in the journal fillet radius.

As the report is not designed to assess fault or to determine civil or criminal liability, but instead to advance transportation safety, there are no recommendations in this instance.

The report does identify its findings as to potential risk noting: Without alternate strategies to identify fatigue cracks in the journal fillet radius or to predict the likelihood of cracks developing, problematic axles might not be removed from service in a timely manner, increasing the risk of broken-axle derailments.

With the final reference related to Safety Action indicating that the Board is currently unaware of any safety action that has been as a result of this occurrence.

You can review the entire report here.

The information notice related to the release can be examined here.


For more items of interest related to CN Rail service across the Northwest see our archive page here.

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