Source thestar.com

Petroleum crude oil is categorized as a Class 3 Dangerous Good, and can be divided into three packing groups, depending on the level of safety hazard. The oil on the Lac-Mégantic train was identified for transportation from North Dakota as Packing Group III, the least hazardous in that class.

The TSB said the crude oil that was transported by Montreal, Main & Atlantic Railway was documented as a Class 3 Dangerous Good (flammable liquid), group 3, when it should have been classified as a more volatile group 2 product. Officials with the TSB said the classification impacts what kind of container the product is shipped in.

"The lower flash point of the crude oil explains in part why the crude oil ignited so quickly once the Class 111 tankers were breached," TSB investigator Don Ross said in an interview September 11, 2013. Ross said the TSB investigation into the derailment is ongoing. The TSB investigation has previously said that a lack of adequate braking onboard the train could have caused the derailment.