Canada’s lead railway safety investigator believes broken pieces of track were at play in two Canadian Pacific Railway oil train derailments that happened less than two months apart near the same Saskatchewan community.
“While both investigations are ongoing, in both cases, the suspected cause appears to be related to a broken rail,” Dan Holbrook, the Transportation Safety Board of Canada (TSB)’s acting director of rail investigations, recently wrote in a letter to Canadian rail safety regulators.
Both CP Rail trains were carrying oil from ConocoPhillips and jumped the tracks on separate — but close-by — portions of CP Rail’s Sutherland subdivision.
The first fiery derailment happened on Dec. 9, 2019, just east of Guernsey, a small hamlet of about 100 people located 114 kilometres east of Saskatoon.
The second incident happened on Feb. 6 west of Guernsey, prompting an evacuation of the community.
Combined, the two crashes leaked an estimated 3.1 million litres of oil — more than 12 times the amount of product believed to have leaked during the 2016 Husky Energy pipeline spill near Maidstone, Saskatchewan (up to 250,000 litres).
Each train derailment sparked a fire that tied up first responders for more than 24 hours and closed off vehicles to the affected portion of Highway 16 for a time.
Physical evidence of broken rail
Holbrook’s letter — written to the director general of rail safety at Transport Canada and recently posted to the TSB site — cited physical evidence of a broken rail found at the site of the second derailment.
“On the north side of the train, impact marks were observed on the wheel treads of tank cars located in the 28th, 29th and 31st positions behind the head-end locomotive,” Holbrook wrote.
“The marks observed were consistent with impact that occurs when a wheel tread contacts a broken rail.”
A table in Holbrook’s letter listed the cause of both Guernsey derailments as “suspected broken rail.” Holbrook did not specify what evidence found at the site of the first crash led him to believe a broken rail was involved in that incident.
Holbrook cited the twin Guernsey derailments in a list of seven Canadian oil train derailments since January 2015 that happened, “as a result of a broken rail, broken joint bars or other track infrastructure condition.”
Tank car failure
Holbrook mentioned that the second derailed CP Rail train near Guernsey was using the latest crash-resistant oil tank cars, which have been championed in recent years by Transport Canada.
“Despite using the best tank cars available, about 27 of the tank cars released an estimated 1.6 million litres of product,” he wrote.
“This suggests that the recent tank car design improvements alone are insufficient to fully mitigate the risk of adverse consequences resulting from derailments involving dangerous goods.”
Jean-Pierre Gagnon, a retired Transport Canada engineer, said more information is needed.
“[It’s] hard to conclude much without knowing the damage they sustained, how long the cars released, how much of the release is a result of initial damage and how much is the result of the fire,” he said.
“Tank cars that survive the derailment often fail and lose their contents as a result of the fire impinging on the tank and inducing thermal failures.”
Other factors already ruled out
Interim updates previously posted by the respective TSB investigators probing each Guernsey-area crash preliminarily ruled out some potential crash factors, including mechanical defects.
Each of those updates also stated that “a review of the locomotive event recorder download determined that the train was handled in accordance with regulatory and company requirements.”
“Therefore,” according to a recent update on the probe into the first derailment, “the investigation will focus primarily on the Sutherland Subdivision track infrastructure and maintenance activities.”
CBC News has reached out to CP Rail for comment about Holbrook’s letter.