The Transportation Safety Board of Canada has released a report of its findings after investigating a Canadian National derailment that occurred on February 18, 2020 at Emo, Ontario, northeast of the Minnesota border. The 144-car train included 38 cars of crude oil. A total of 33 cars derailed, and 29 of those carried crude oil. The investigation determined that six of those cars were leaking, and they ultimately released 84,464 gallons of crude onto the surrounding landscape. There were no injuries or fires reported from this derailment.
The temperature was approximately -17 degrees Fahrenheit, and the train went into emergency braking as it was rounding a four-degree left-hand curve while traveling at 44 m.p.h. Also, the train was rolling over a rail-highway crossing (Ontario provincial highway 602 public automated crossing) when it went into emergency.
The report notes that “smearing and gouging” was seen on the wheel rim faces of the several of the derailed tank cars. When the wheels left the rails, they landed between the rails, and pushed the rail out of gauge as they moved forward.
Additional inspection discovered a build-up of snow and ice between tie plate rail seats and the underside of the rail base. This resulted in the rail becoming separated from the tie plate, creating the possibility of a loaded train spreading the rail, which is exactly what caused this derailment. This circumstance is referred to as “ice jacking.”
The Transportation Safety Board of Canada included the following discussion of ice jacking in it’s report:
“A combination of weather conditions and track conditions is required for ice jacking to develop. In winter, roadway snow clearing activities frequently push road sand, salt, and snow off to the ends of a crossing and onto railway tracks. The presence of road salt can accelerate snow melt, which sometimes leaves water pooling alongside the track. When the track is exposed to freeze/thaw cycles, this can contribute to ice build-up along the base of the rail.
“When water is present, the passage of trains produces a pumping action that can promote water ingress between the underside of the rail base and the tie plate rail seat, where the water freezes. When a number of these cycles occur, it can produce a build-up of ice that physically lifts the rail from the tie plate rail seat, which makes the rail susceptible to gauge spreading when subjected to loading as a train passes. The TSB has observed this phenomenon in at least 1 other investigation. (TSB Railway Investigation Report R11V0057.)
“Although railways are aware of this condition and track supervisors are trained to recognize it, the condition can still be difficult to detect during a visual track inspection when snow is present.“