CALGARY -- Instability in the track caused a 2019 train derailment in southern Alberta, according to a report issued by the Transportation Safety Board of Canada Friday.
The derailment, which took place in Irvine, Alta., on Aug. 2, 2019, caused a chemical spill and grass fire, which forced approximately 300 people to evacuate their homes, and closed part of the Trans-Canada Highway.
Five cars contained dangerous goods, including flammable liquids.
According to the report, the temperature on Aug. 2, 2019 was 34.5 C, just below the benchmark of 35 C, at which point a train is instructed to slow to a maximum speed of 48.2 km/h (30 mph).
At the time of the derailment, the train was traveling at a speed of "about 60 km/h (37.3 mph) on the Maple Creek Subdivision when the mid-train remote control locomotive and the following 21 cars derailed."
Two cars turned on their sides and were leaking styrene monomer "at a slow rate." A third car, containing residual methanol, was badly damaged," including tears in the tank", but nothing spilled from it.
Firefighters on scene were able to douse the grass fire. No one was injured in the incident.
A camera on the lead locomotive captured a shot of the spot on the tracks where the train derailed.
The tracks were repaired within a day and rail transport was able to resume Aug. 3.
According to the report, earlier inspections and repairs had been done on the tracks in the area.
In its summary, the TSB said, "The urgent track geometry identified in the 24 July 2019 inspection indicated that the subgrade beneath the north rail had settled. These defects were unrelated to the previous tight rail condition in the general area that had been identified and corrected in April, 2019. The railway stabilized the track by surfacing it on 25 July 2019 and applied a TSO." The track was also inspected.
"Despite the repair work and inspections," it concluded, "the track subgrade remained unstable and the track was therefore more susceptible to the effects of increased longitudinal forces produced by high ambient temperatures."
