MONCTON, NB, 19 June 2015 /CNW/ - In its investigation report (R14M0002) released today, the Transportation Safety Board of Canada (TSB) determined that a wheel with an undetected defect broke, leading to the January 2014 derailment and fire involving a Canadian National (CN) train near Plaster Rock, New Brunswick.
On 7 January 2014, a CN freight train travelling from Toronto, Ontario, to Moncton, New Brunswick, derailed 19 cars and 1 mid-train locomotive near Plaster Rock. Seven Class 111 tank cars carrying petroleum crude oil and other dangerous goods, and 5 Class 112 pressurized tank cars carrying butane were among those that derailed. Approximately 230,000 litres of crude oil spilled from the tank cars and caught fire. About 150 residents were evacuated within a 1.6 kilometre radius of the fire. A total of 350 feet of track was destroyed, and there were no injuries.
The investigation determined that a wheel on the 13th car shattered due to an area of subsurface porosity that led to fatigue cracking. The subsurface porosity was not detected during the ultrasonic testing when the wheel was manufactured in 1991, or when it was reprofiled in 2006. The broken wheel and the wheel on the opposite side of the same axle derailed inside the track gauge, causing track damage leading to the derailment of the 19 cars and the mid-train locomotive.
The derailed cars included 4 older Class 111 tank cars, 3 Class 111 tank cars built to the CPC-1232 standard, and 5 Class 112 pressurized tank cars. The couplers of other cars punctured 2 of the older Class 111 tank cars, causing them to release their contents and feed a large pool fire. The CPC-1232 cars fared better, although it was difficult to determine whether their performance was attributable to the enhancements or simply to their position in the train and the types of impacts they sustained. The Class 112 cars did not sustain any impact damage. However, the pressure relief device gaskets on 2 Class 112 cars and 1 Class 111 car degraded due to heat from the pool fire, causing some product to be released from these cars.
The investigation also found that appropriate and effective measures were taken in response to the emergency. The environmental response plan and derailment site remediation ensured a minimal and contained environmental impact.
Transportation of flammable liquids by rail is a TSB Watchlist issue. The TSB is calling on railway companies to conduct route planning and analysis, and perform risk assessments to ensure that risk-control measures are effective. This accident also underscores the TSB's longstanding call for tougher standards for tank cars transporting crude oil to reduce the likelihood of a dangerous goods release during accidents. On 1 May 2015, Transport Canada introduced new regulations for a more robust tank car standard, retrofit requirements and an implementation timeline.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
SOURCE Transportation Safety Board of Canada
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