Charpy impact testing showed that the normalized steel in the tank shell of the punctured chlorine car had a fracture toughness that was significantly greater than the fracture toughness of the non-normalized steels of the catastrophically ruptured tank cars involved in the derailment of a Canadian Pacific Railway freight train in Minot, North Dakota, in January 2002. The steel in the Minot tank cars exhibited relatively low fracture toughness, and cracks propagated rapidly around the circumference of each tank. The higher fracture toughness in the Graniteville tank car contributed to the relatively quick arrest of the crack even though there was brittle fracture in its outer portions.