The DOT-111 is a staple of the American freight rail fleet. But its flaws have been noted as far back as a 1991 safety study. Among other things, its steel shell is too thin to resist puncturing in accidents, which almost guarantees the car will tear open in an accident, potentially spilling cargo that could catch fire, explode or contaminate the environment.
"It's too early to tell. There's a lot of factors involved," Ross said. "There's a lot of energy here. The train came down on a fairly significant grade for 6.8 miles before it came into the town and did all the destruction it did." He said the train was moving at 63 mph (101 kph) when it derailed.
Officials were also looking at a locomotive blaze on the same train in a nearby town a few hours before the derailment. Ross also said the locomotive's black box has been recovered, and investigators were examining whether the air brakes or the hand break malfunctioned.
"The extent to which (the fire) played into the sequences of events is a focal point of our investigation," Ross said.
The Saturday blasts destroyed about 30 buildings, including a public library and Musi-Cafe, a popular bar that was filled with revelers, and forced about a third of the town's 6,000 residents from their homes. Much of the area where the bar once stood was burned to the ground. Burned-out car frames dotted the landscape.
The derailment raised questions about the safety of Canada's growing practice of transporting oil by train, and was sure to bolster arguments that a proposed oil pipeline running from Canada across the U.S. — one that Canadian officials badly want — would be safer.
Raymond Lafontaine, whose son and two daughters-in-law were among the missing, said he was angry with what appeared to be a lack of safety regulations.