RICHMOND HILL, ON, Nov. 5, 2015 /CNW/ - The Transportation Safety Board of Canada (TSB) today released its investigation report (R14T0160) into the 10 July 2014 derailment of a Canadian National Railway (CN) freight train near Brockville, Ontario. The 26 derailed cars included 13 Class 111 tank cars, which contained aviation fuel residue. A small amount of product was released and no injuries were reported.
The investigation determined that the derailment occurred as a result of excessive "truck hunting" on an empty 80-foot long centrebeam bulkhead flat car. These types of freight cars are less rigid than other types of cars and are known to be more susceptible to excessive truck hunting. "Truck hunting" is a term used to describe the side-to-side movement of wheel sets within a freight car truck. Under certain conditions, the truck hunting can become excessive which can cause wheel lift or wheel climb, either of which can cause a derailment.
In this case, the excessive truck hunting was influenced by the type of car, the speed of the train (60 mph), the worn condition of the constant contact side bearings (CCSB), as well as by the truck type. When car inspectors visually inspect these cars, they look for contact between the CCSB and the car body underframe. However, the investigation determined that visual inspections alone cannot verify if a CCSB is actually providing effective support.
The damaged Class 111 tank cars contained only residue amounts of product and, consequently, only a small amount of product was lost. However, the damage observed in this derailment was consistent with the damage observed to Class 111 tank cars in other TSB investigations. The potential for catastrophic environmental impacts and loss of life remains, thereby reinforcing the need for improved tank car design standards.
The transportation of flammable liquids by rail has been identified as one of the key risks to the transportation system and it is included on the TSB's Watchlist. The TSB has been pointing out the vulnerability of Class 111 tank cars for many years, and the Board has called for tougher standards for all Class 111 tank cars, not just new ones, to reduce the likelihood of product release during accidents. Although both the United States Department of Transportation and Transport Canada have introduced new retrofit requirements and timelines, until flammable liquids are transported in tank cars built sufficiently robust to prevent catastrophic failure when involved in an accident, the risk will remain high.
Following the occurrence, the TSB issued a Rail Safety Advisory identifying that empty 80-foot long centrebeam bulkhead flat cars, which are used throughout North America, may be more susceptible to excessive truck hunting. For its part, CN introduced a 45 mph speed restriction on such cars and upgraded all similar cars within its fleet.
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.
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SOURCE Transportation Safety Board of Canada
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