The crude oil carried in tankers that derailed and ignited in Lac-Mégantic, Que., in July was misidentified as a less volatile substance, the Transportation Safety Board of Canada announced this morning.

At a news conference in Ottawa, the lead investigator on the rail disaster, Donald Ross, said that inaccuracy, "explains in part why the crude ignited so quickly once the train cars were breached."

The revelation comes after tests were conducted on oil contained in nine train cars belonging to Montreal, Maine & Atlantic railway that were not involved in the explosion.

Dangerous goods

Flammable liquids included in Class 3, Flammable Liquids, are in one of the following packing groups:

  • Packing Group I, if they have an initial boiling point of 35 C or less at an absolute pressure of 101.3 kPa and any flash point;
  • Packing Group II, if they have an initial boiling point greater than 35 C at an absolute pressure of 101.3 kPa and a flash point less than 23 C; or
  • Packing Group III, if the criteria for inclusion in Packing Group I or II are not met.

Source: Transportation Safety Board of Canada

The 72-car, unmanned train rolled down an incline into the core of the town, left the tracks and exploded early in the morning on July 6. The blast and fires killed 47 people and destroyed several blocks neighbouring the train tracks.

The TSB said it was immediately issuing safety advisory letters to rail authorities in Canada and the U.S., where the train originated, to review the processes for suppliers and companies transporting dangerous goods to ensure the description of the products are accurate and documented properly.

It has previously issued two such advisories, both concerning the risks of unattended freight trains.

The crude oil in the Montreal, Maine & Atlantic train that derailed in Quebec had been listed as packing group three, the least hazardous on the scale.

The oil actually had the properties of a packing group two substance, which also includes goods like gasoline, that have a lower flash point and will therefore ignite more quickly.

It's the responsibility of the importer, in this case New Brunswick-based Irving Oil, to ensure the description of the products are correct, Ross said.

Federal Transport Minister Lisa Raitt said officials will be reviewing the TSB's advisory as soon as possible.

Impact not yet known

"If a company does not properly classify its goods, they can be prosecuted under the Transportation of Dangerous Goods Act," Raitt said in a statement.

Ross said the response by firefighters in Lac-Mégantic would not have been affected by the misidentification of the packing group and the tankers used to ship the crude wouldn't have necessarily have been changed if the oil had been correctly identified.

"It’s a possibility that it had no effect, but we’re not saying that yet," he said.  

The TSB investigation is ongoing and the various failures of the tanker cars themselves are still being evaluated, Ross said.