Published: August 25th 2010
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The TSB warned today that tens of thousands of faulty railway cars may be in operation, hauling dangerous goods across Canada.
In its final report (R09W0016) into a 2009 accident near Dugald, Manitoba, the TSB says a faulty stub sill went undetected, allowing a tank car loaded with 51 500 pounds of flammable liquid propylene to separate from the rest of the train before coming to a stop. A stub sill is part of the frame which connects the tank cars.
Although the Dugald train came to a stop without derailing, the TSB says the lack of formal protocols to record and report stub sill failures may prevent other broken parts from being found before the next accident.
"Approximately 41 000 cars within the North American tank car fleet are equipped with this model of stub sills, and approximately 35 000 of them are in dangerous goods service," said Rob Johnston, Acting Rail/Pipeline Director of Investigations. "And although these represent just 13 per cent of the tank population, they account for 34 per cent of the cracked stub sills and 100 per cent of the broken ones in Canada. These numbers are alarming and must not be ignored."
The TSB further noted that in many cases the regulator, Transport Canada (TC), was either unaware of, or had limited information regarding stub sill failures so the problem went undetected.
"When tank cars and dangerous goods are involved, what we don't know can sometimes hurt us," added Mr. Johnston. To combat the problem, the Board recommends that TC take the lead in coordinating with the railway industry and other North American regulators on the issue of reporting stub sill failures.
Adding to the risk, the Board says today's trains are longer and heavier than ever, making them more difficult to control. Alarmingly, the Board found that stub sills manufactured according to older design criteria may be more susceptible to failure in the current operating environment of longer heavier trains.
Prior to the mid-1990s, an average train in main-track service was about 5000 feet long and weighed 6000 to 7000 tons. Today, some of them are over 12 000 feet long and weigh more than 10 000 tons.
"That's a big difference," explained Johnston. "Trains and car design criteria must evolve over time and keep pace with operational demands or accidents may happen. This is a major safety concern."
Earlier this year the Board included the operation of these longer heavier trains on its safety Watchlist. The list, which highlighted nine transportation issues posing the greatest risk to Canadians, also offered several solutions-including better marshalling of longer heavier trains and detailed risk assessments whenever operating practices change.
In the interim, Johnston said there is still more work to be done. "The recommendation we've made today is the first step in this direction," he said. "Raising the safety standard will take a concerted effort from both TC and the railway industry."
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.