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The Transportation Safety Board of Canada (TSB) recently issued recommendations about the removal of certain wheel sets as part of its final investigation report on Canadian Pacific Railway's derailment near Buckskin, Ontario, in January 2006.

The board determined a freight car derailed when a wheel became loose while negotiating a curve and migrated inboard on its axle, causing both wheels to drop between the rails. Undetected wheel damage and other factors caused the wheel to progressively loosen.

The wheel set was produced at Canadian National Railway Co.'s Transcona shop between 1998 and 2001 using a modified wheel boring process. The shop produced about 43,000 wheel sets using the process. Since 2000, at least 18 of the wheel sets caused derailments in Canada and an unknown number outside the country, the TSB said.

Because the wheel sets have a "high susceptibility to loosen, particularly in heavy-curvature territory," the board recommends that Canada's Department of Transport ensure all 36-inch Transcona shop wheel sets assembled between April 1998 and February 2001 be removed from rail cars operating in Canada.

The board also recommends that transport department ensure railroads adopt procedures and technologies to track all wheel sets.

"The industry has no effective way to track wheel sets once they are removed from their original car, [so] wheel sets with potentially defective components cannot be easily located and removed from service before failure," TSB officials said in a prepared statement. "The inability to quickly locate defective wheel-set components increases the risk of a failure, which can lead to a derailment."