The cause of a 2019 CP derailment has been determined.
In its investigation report (R19E0147) released recently, the Transportation Safety Board of Canada (TSB) found that an undetected internal rail defect led to a main track train derailment near Blackfalds, Alberta in the fall of 2019.
On 27 September 2019, at approximately 2236 Mountain Daylight Time, a Canadian Pacific Railway (CP) train was travelling southward at approximately 22 mph on the Leduc Subdivision when it derailed nine tank cars carrying flammable liquids at Mile 7.52 near Blackfalds, Alberta. As a result of the derailment, three of the tank cars released petroleum products. There were no injuries or fire. Appropriate measures were taken by the railway, local first responders and federal and provincial authorities to protect the site and ensure public safety immediately following the derailment.
The investigation found that the derailment took place when a sudden failure of the rail occurred under the train, due to an undetected transverse detail defect. Over time, the defect had grown to a critical size, and the rail broke when it could no longer support the load of the passing train. It was determined that despite frequent ultrasonic rail testing for internal rail defects, including a test conducted 30 days before the derailment, the defect remained undetected. The rail surface condition adversely affected the ability of the inspection equipment to detect internal defects. A rail grinding program was insufficient to remove rail surface contamination and defects prior to the ultrasonic inspection. Additionally, although lateral wear on the rail exceeded railway requirements and therefore required the rail to be removed from the track, the rail remained in service until an undetected defect progressed to the point of failure.
The three cars that released product were DOT/TC-111 cars that were compliant with specification CPC-1232. While only three cars lost product, there was potential for more catastrophic consequences. The requirement to transport all Class 3 flammable liquids in DOT/TC-117 tank cars, which are built to a more robust standard than DOT/TC-111 cars, do not take effect until 1 May 2025. Until all Class 3 flammable liquids are transported in more robust tank cars, loss of product is likely to continue to occur in derailments, even at relatively low speeds, perpetuating the risk of significant damage to persons, property, and the environment.
Following the occurrence, CP upgraded the track infrastructure in the area where the occurrence took place. Transport Canada issued Ministerial Order 20-10, which provided additional requirements to operate a “higher risk key train” including speed restrictions based on temperature rather than time of year. To do so, railways must have winter operating risk mitigation plans that include a rail grinding frequency to ensure rail surface conditions do not hinder the detection of internal rail defects.
The TSB conducted a limited-scope, fact-gathering investigation into this occurrence to advance transportation safety through greater awareness of potential safety issues.
See the investigation page for more information.