PLASTER ROCK, N.B. - A broken wheel was a factor in the derailment of a freight train that caught fire earlier this year in northwestern New Brunswick, the Transportation Safety Board said Thursday as it released an update on its investigation.
The CN (TSX:CNR) train was hauling crude oil and liquefied petroleum gas when 19 cars and a locomotive went off the tracks Jan. 7 near the village of Plaster Rock, sparking a fire that burned for days.
The board said early on that its investigation would centre on a cracked wheel near the front of the 122-car train, which was en route to Moncton, N.B., from Toronto when it derailed.
Ian Perkins, a senior investigator based in Dorval, Que., said the wheel remains a focal point.
"We know any accident has multiple causes," he said in an interview. "We know the wheel definitely played a role. To say the wheel equalled the derailment, we're not at that point yet."
No one was hurt in the derailment, but 150 people in the surrounding area were forced from their homes as the fire burned.
The board said the wheel, located on the 13th car, was manufactured in 1991 and had a crack under its surface that led to a shattered rim.
Perkins said investigators know the wheel came off the track about 16 kilometres before the other cars derailed.
"From then, that 10-mile period up to where the pileup occurred, there were multiple broken rails and multiple ... spots where the base of the rail got battered," he said.
Perkins could not say how long the crack had been there, but he said it "was due to a porosity ... back during the manufacturing process."
"It's not a build defect, it's a quality control issue," he said. "In that sense, we haven't been able to identify if it's a systemic issue."
The board said wheels manufactured today are subject to ultrasonic inspections to check for areas of porosity. Wheels with "significant areas of porosity" are prevented from being placed into service, it said in an update posted on its website.
The board also said two older DOT-111 cars built in 1984 and 1996 were the primary source of the oil spill that led to the fire.
The federal government has promised to pull all DOT-111s off Canada's rails over the next few years.
Perkins said the next step in the investigation is to review the broken wheel's history and the manufacturing process. The train's crew will also be interviewed and the damaged cars will be examined.
Once the investigation is complete, the board will write and a release a report into the derailment. Perkins could not say when that would be.