The oversight of instructions on train engine operations led to flames jumping from a CN Rail train that caused a large grass fire in southeast Calgary, a federal report has concluded.
In the early morning of July 17, 2021, a train carrying 37 loaded cars was heading northeast through southeast Calgary from the CN Sarcee Yard when crew members noticed flames and embers erupting several meters into the air from the stacks of locomotive 7524.
Those embers ignited a grass fire on the adjacent right-of-way about 725 yards from 36 St. SE extended to Mount Erin Cres. pedestrian crossing.
The grass fire was extinguished about seven hours later by teams from the Calgary fire department.
No one was injured, there were no dangerous goods involved in the incident and the track was not damaged.
Locomotive 7524 was inspected a week later at the company’s locomotive shop in Edmonton by CN personnel, accompanied by officials from the Transportation Safety Board of Canada.
It focused on carbon build-up in its exhaust stacks and found that two of the engine’s power assemblies may have been misfiring.
“As a result, unburnt diesel fuel was ejected into the exhaust system during the exhaust cycle. Once in the exhaust system, the diesel ignited, causing a fire in the locomotive’s exhaust stack,” the TSB report said.
“It is likely that some of the carbon deposits present at the time of the incident ignited, creating embers that were expelled from the locomotive exhaust stack before the flames were noticed by the crew.”
The investigation also found that the locomotive had been idling 24 hours before the shift that led to the fire and that it had not been sufficiently started to clean carbon deposits “contrary to CN instructions”.
Diesel engines such as locomotive 7524 are equipped with a smart starting feature that prevents them from idling for long periods.
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“HHowever, the function was disabled because the locomotive had weak batteries and restarting the engine might have been difficult if it had been switched off,” the TSB said.
The locomotive was inspected at CN’s Edmonton shop a month before the fire and underwent three safety inspections in Calgary in the days before the incident, but its weak batteries were not replaced, the federal agency said.
“At the time of the incident, CN inspected the exhaust system at least every 30 days on locomotives equipped with supercharged engines,” the TSB report said.
After the incident, the two power units on the locomotive were replaced and the fire, along with other recent incidents, led Transport Canada to introduce the Railway Extreme Heat and Fire Risk Rule, which came into effect 11 months later.
The rule includes requirements for exhaust system inspections, right-of-way fire mitigation and lane integrity during times of extreme heat.