Safety Advisory Follows Report on Canadian National Derailment
The Transportation Safety Board of Canada's investigation determined the derailment occurred because of excessive "truck hunting" on an empty 80-foot long centerbeam bulkhead flat car.
The Transportation Safety Board of Canada last week released its investigative report on the July 2014 derailment of a Canadian National Railway freight train near Brockville, Ontario. Thirteen of the 26 cars that derailed were Class 111 tank cars containing aviation fuel residue; the board reported a small amount of product was released and no injuries were reported.
Another CNR train carrying crude oil derailed and spilled some of the oil in western Wisconsin about 2 p.m. Nov. 8, the Milwaukee Journal Sentinel reported.
TSB's investigation determined the July derailment occurred because of excessive "truck hunting" on an empty 80-foot long centerbeam 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," according to the board, which said "truck hunting" is a term used to describe the side-to-side movement of wheel sets within a freight car truck. It can become excessive and cause wheel lift or wheel climb, both 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, 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," according to the board’s news release. "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 board has issued a Rail Safety Advisory stating that empty 80-foot long centerbeam bulkhead flat cars, which are used throughout North America, may be more susceptible to excessive truck hunting. And CNR has introduced a 45 mph speed restriction on such cars and upgraded all similar cars within its fleet.