Gainford CN derailment caused when fatigued track snapped, TSB says

A CN derailment near Gainford in October 2013 was caused when a worn track with significant metal fatigue snapped, according to a Transportation Safety Board report released Tuesday.

The derailment happened on a siding track along a 600-foot curve near the village of Gainford, west of Edmonton.

After the accident, the TSB took sections of the track into the laboratory and found 16 defects in pieces submitted for examination, said George Fowler, a civil engineer who works as a track and infrastructure specialist with the TSB.

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“It is a significant number of defects for a curve like this, for a track like this, though it is a siding," Fowler said.

More than 120 people were evacuated from the hamlet for four days.

CN used what is called a vent-and-burn process after the derailment. In such cases, crews explode a controlled charge at one end of the tanker to let the vapour escape, then blow a hole in the other end and allow the liquids to drain into excavated pits, where it then burned off.

Fowler said the siding tracks had been tested four times in the months before the derailment, though it was only required to be tested once.

Such tests are done by contractors hired by the railway. They use ultrasound equipment to study the rails and detect internal defects in the steel.

“As good as it is, it has limitations,” Fowler said of the technology.

In the Gainford derailment, Fowler said, the surface of rail in question was in such bad condition that ultrasound signal couldn’t properly penetrate and therefore did not detect internal cracks.

Such cracks, he said, start on surface and over time become what are called "transverse defects," meaning they spread down through the body of the track. When the TSB studied the section that snapped, it found that 31 per cent of the rail was no longer intact.

Such defects grow over time, and when the rail can no longer support the load it snaps and causes a derailment. That’s what happened in this case, Fowler said.

“These types of defects are not that common, thankfully,” he said.

In total, 13 cars went off the tracks near Gainford. Four tanker cars were carrying crude oil and nine were carrying liquid petroleum gas. Each of the latter carried 130,000 litres of LPG.

During the accident, one tanker was punctured by the coupler from a second car. Two tankers caught fire and exploded in a fireball that spread across Highway 16.

Fowler said the lifespan of each rail depends on two factors: wear and metal fatigue.

Rail wear is much easier to determine than fatigue, he said, which can only be detected by using ultrasound.

The rail that snapped was laid down in the 1970s and was approaching its expected lifespan. It was scheduled to be replaced this year.

Fowler said the TSB report did not find that the rail in question should have been replaced before the accident.

“Railroads can’t replace every piece of rail they want to,” he said. “Railroads are good businesses, they’re not going to replace an asset before they have to.”

Asked what his main recommendation would be to prevent similar derailments in future, Fowler pointed to rail maintenance. If rail surfaces are kept clean and smooth, he said, the ultrasound can better penetrate the steel and detect internal defects.

“Not all defects will be detected every time,” he said.

Taxidermist Jeanette Hall, whose home and studio were across the highway from the derailment site, said railways are using outdated equipment and technology and are risking lives to move goods that might better be transported through pipelines.

"They are hauling around ticking time bombs," she said. "I think they need to understand that human safety comes before what they're hauling. Use better cars or put this stuff underground."

Hall said she found it too difficult to return to her home in Gainford and now lives in Wildwood, about 30 kilometres west.

"We can still hear the train from the house, but it's far enough away that if something should happen, it's not going to affect us directly," she said.

"You can't get away from trains. We looked at houses everywhere. It doesn't matter where you go you're going to come across train tracks."

The train that derailed was travelling to Vancouver from Edmonton at a normal speed of 35 km/h when those 13 cars left the tracks.