2021 derailment near Edmundston, NB, highlights the importance of cross key design and inspection
Dartmouth, Nova Scotia, 1 February 2022 — Today, the Transportation Safety Board of Canada (TSB) released its investigation report (R21M0002) into a derailment near Edmundston, New Brunswick, drawing attention to the importance of reassessing the design and inspection frequency of critical rail components, such as cross keys, based on changes in railway operating conditions.
On 26 January 2021 at approximately 2030 Atlantic Standard Time, 22 cars of a Canadian National Railway Company (CN) train derailed about 13 km southwest of Edmundston, NB. There was no fire, and no injuries were reported. Although eight of the derailed cars were carrying dangerous goods, none were released.
The investigation found that the train derailed when a rail car struck a coupler that had fallen from the leading end of the preceding car. It was determined that the coupler fell after the cross key, a rail car coupler component, that was retaining it in place failed in service. The failed cross key had developed fatigue cracks at the inside radii, which likely occurred over its 4 years of service before the derailment. It is likely that the design of the specific cross key contributed to the initiation and propagation of the fatigue cracks.
The investigation also identified that there is no prescribed interval for the inspection of cross keys installed on rail cars equipped with long travel hydraulic end-of-car cushioning devices (EOCCDs), like those involved in this occurrence. The cross keys generally remain in service for many years, and are only replaced when they are worn beyond set limits or develop a condemnable defect. Cross keys in EOCCDs are not easily accessible for inspection in the field due to the design of EOCCDs. Consequently, they are usually only inspected when work takes place on the draft assembly.
Following the occurrence, CN initiated a proactive cross key inspection program for rail cars having the same manufacturer, draft gear design and manufacturing timeframe as the occurrence car. Of the 604 rail cars inspected, 408 were found to have a defective cross key. In addition, the component manufacturer revised the cross-key geometry by increasing the radius in the area in which cracking had occurred in order to lower stresses and improve performance. The updated cross keys are currently undergoing service trials.
See the investigation page for more information.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada