An undetected internal rail defect caused a train derailment near Blackfalds in September 2019, say Transportation Safety Board of Canada investigators.
A Canadian Pacific Railway train was travelling south when nine tank cars derailed about five kilometres south of Blackfalds at around 10:30 p.m. on Sept. 27, 2019. Three tank cars leaked petroleum products. There were no injuries or fire.
“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,” says a TSB release on Monday. “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.”
The TSB says that despite ultrasonic rail testing designed to stop those kinds of defects — including a test done only 30 days prior to 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.”
While only three of the tanker cars spilled petroleum “there was potential for more catastrophic consequences,” says the TSB.
Safety changes that will require all Class 3 flammable liquids to be transported in tanker cars built to a stronger standard do not kick in until 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,” says the TSB.
Following the derailment, CP upgraded the tracks in that area. Transport Canada issued an order requiring additional safety measures to operate a “higher risk key train,” including speed restrictions based on temperature rather than the time of year.
Railways must also 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.
Last month, a CP rail train derailed just south of Lacombe near Hwy 2A and Range Road 270A (between Lacombe and Blackfalds). About 22 rail cars derailed, spilling tar oil used for the asphalt-making process, as well as lumber around 8 p.m. on July 2.
Residents of three nearby houses were initially evacuated but soon returned home.
About 32,000 litres of tar oil was spilled. No injuries were reported.
That incident remains under investigation.