Alta. Newspaper Group
Heat that caused rails to expand and push on an already unstable bank led to a train derailment that forced the evacuation of Irvine one year ago, according to investigators.
The Transportation Safety Board released its findings on Aug. 21 into the Aug. 2, 2019 derailment of 21 cars, including five that carried dangerous goods, east of Medicine Hat.
It states that Canadian Pacific construction crews had added ballast in the spring, then worked in the area two weeks before to surface a bump off about 3 centimetres (1.5 inches) on one rail. That work passed inspection and subsequent checks.
“Despite the repair work and inspections, the subgrade remained unstable and the track was therefore more susceptible to longitudinal forces produced by high ambient temperatures,” the report concludes.
The temperature on the afternoon of Aug. 2, 2019 was 34.5C, and when brakes on the eastbound train came on, the derailment occurred accordion style.
Emergency crews, including local and CP teams, responded shortly after 3 p.m.
The nearby Trans-Canada Highway was closed until 11 p.m. on the busy Friday before the August long weekend.
Authorities also evacuated a seven square-kilometre area around the site, including the Hamlet of Irvine, with 300 residents.
A small grass fire was put out and crews found that two of three tank cars that contained styrene monomer were damaged and slowly leaking while one of two empty tank cars that contained methanol was torn open.
Damaged cars were emptied over the next week. The rail line reopened at 10 a.m. the next day.
The train, which had a two-person crew, was found to be in good working order.
Transportation Safety Board reports do not assign fault, according to an included disclaimer.