Backgrounder - Final Investigation Report R04Q0040 August 17, 2004 Derailment of CN Train U-781-21-17 near Lévis, Quebec
At approximately 1440 eastern daylight time on August 17, 2004, 18 tank cars of Canadian National Train U-781-21-17, a petroleum product unit train travelling from the Ultramar Canada Inc. refinery at Lévis, district of Saint-Romuald, Quebec, en route for Montréal, Quebec, derailed at Mile 3.87 of the Lévis Subdivision, in the marshy area of the Grande Plée Bleue, near Saint-Henri-de-Lévis. Approximately 200 000 litres of gasoline and diesel fuel spilled into the marshy area, but the spilled product was recovered. There were no injuries.
The Transportation Safety Board of Canada (TSB) investigation found that the soil under the track sustained a sudden punching failure, causing the track to collapse and the cars to derail. The track was built on saturated peat, which was subject to settlement under repeated loads which gradually resulted in distortion and realignment of peat fibres, which most likely led to the sudden punching failure.
Axle weight, tonnage and train speed are factors that would contribute to the punching phenomenon. Current railway inspection procedures, based on surface observations, are not able to detect the impending risk of collapse.
A significant spill of petroleum products occurred when the tank car shells and heads were breached during the derailment. The punctures to the tank cars occurred even though the ground at the derailment site was marshy and therefore soft. The type of car involved in this occurrence has been identified as vulnerable to puncture in previous accidents.
Industry has developed standards to enhance puncture resistance for new tank cars with a gross weight of 286 000 pounds, but these do not apply to tank cars with a maximum gross weight of 263 000 pounds, the type involved in the occurrence.
The Board made the following recommendations in the report:
The Department of Transport and the railway industry conduct in-depth studies on the behaviour of saturated organic materials under cyclic loading.
The Department of Transport extend the safety provisions of the construction standards applicable to 286 000-pound cars to all new non-pressurized tank cars carrying dangerous goods.
The final report R04Q0040 is also available on this site.
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