12,000 railway wheel sets prone to loosen:
June 5, 2008
Source: Canadian Press
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Que. — The Transportation Safety Board of Canada says 12,000 wheel sets
still in use by Canadian Pacific Railway, Canadian National Railway and
other North American railroads "have a high susceptibility to loosen"
and should be replaced.
They were among 43,000 suspect wheel sets produced at the Canadian
National Transcona shop, many of which have already been removed from
The board said Thursday its finding arose from an investigation into a
January 2006 derailment of a Canadian Pacific train near Buckskin, Ont.,
when a wheel became loose on a curve and shifted inboard on its axle.
The weak wheel set was produced with a modified boring process used
between April 1998 and February 2001 at the CN wheel shop in Winnipeg.
The board says at least 18 wheel sets made with the modified
pressure-fit technique have been involved in derailments in Canada, plus
an unknown number outside the country.
"These wheel sets have a high susceptibility to loosen, particularly in
heavy-curvature territory," the board says.
"The risk of failure for these remaining wheel sets continues to
increase the longer they remain in service."
It says the Department of Transport should "ensure that all 36-inch
Canadian National Transcona wheel shop wheel sets assembled between
April 1998 and February 2001 be removed from cars operating in
Canada."It also has contacted U.S. rail authorities.
In the Buckskin crash, the board said there was undetected damage to the
wheel and its mounting point on the axle, "leading to micro-movement
that progressively loosened the wheel until a combination of lateral and
rotational forces displaced the wheel inboard."
The derailment damaged 18 kilometres of track as the freight train
continued on its way until the loose wheel set hit a switch, causing 11
additional cars to derail and 130 metres of track to be destroyed. There
were no hazardous goods involved and no injuries resulted.
The board also said Thursday that the industry has no effective way to
track wheel sets once they are removed from their original car, making
it hard to locate potentially defective sets. To fix this, it is
recommending that the railways be required to keep track of all wheel