A broken wheel was the cause of a massive train derailment near Hope, B.C., four years ago.
On Tuesday, the Transportation Safety Board of Canada (TSB) released its investigation into the September 2020 incident, which saw 61 cars of a CN freight train derail.
The TSB said no dangerous goods were involved, though six million kilograms of potash were spilled. The massive wreck happened alongside the Fraser River, and no injuries were reported.
While investigating the westbound train, the TSB said examiners noticed that one train wheel was missing material around the entire circumference.
“The investigation determined that part of the rim of that wheel broke away before the derailment, allowing the wheel to progressively drop between the rails as it continued to rotate, causing the rim to wear down due to friction while in contact with the rail,” the TSB said.
“This reduced the vertical force on a second wheel, which stopped rotating, slid and gradually fell between the rails.
“The lateral pressure exerted against the side of the rail by both derailed wheels ultimately caused the rail to break at multiple weld points and resulted in a pileup derailment.”
The derailment happened on Sept. 14, just after 4:30 a.m., with the freight train travelling at about 80 km/h.
Of the 61 cars that derailed, 58 were breached.
The TSB says its duty is to investigate air, marine, rail and pipeline incidents across the nation.
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