Vol. 17 No. 11
November, 1987
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Stay Safe in 87
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Crews Race Winter to Alter
Avalanches' Course
By Steve Morris
Slow and Easy: To avoid closing the rail line, the new
snowshed at the foot of Mount Stephen is being constructed adjacent to CP Rail's main line through Yoho National
Park - photos by Nicholas Morant.
Field
British Columbia - Trying to alter the course of history may be difficult enough but when you try to alter the
course of nature you're in for a real battle. One need only ask the Calgary Division.
Thirty-five men and machines have been working in this rugged terrain near the Alberta/British Columbia
border to alter a portion of nature's course since May.
ACTIVE PATH
Whether the battle will be won will be determined this winter when a 184-metre-long snowshed at the foot
of Mount Stephen in Yoho National Park is put to the test.
"This area has always been avalanche prone with this path being particularly active in recent years", said
Larry McKee, engineer, buildings and bridges, CP Rail West.
"In order to reduce delays to trains and remove the risk of an avalanche striking a train, we decided to realign
the slide path that the (mud and snow) slides travel down the mountain and construct a protective tunnel or shed.
Building the Chute: One of the most difficult tasks was
building a chute to reduce the force of avalanches, channel them over the snowshed, then divert them away from the
Trans-Canada Highway below.
REDIRECT
Earlier this year, CP Rail awarded the contract for the work to Western Versatile Construction Corporation, of
Surrey, B.C.
"You can't stop slides from happening but what you can do is direct them in such a way as they don't affect your
operation", explained Al Arnold, project engineer, Calgary Division.
One of the obstacles to overcome was building the new shed without interfering or closing the railway's main
transcontinental line. To accomplish this a new line was built adjacent to the existing line.
Ironically, this new line is on part of the same roadbed as the original main line of 1884.
"It was like an archaeological find", Mr. Arnold said. " During the excavation we found the original
wooden timbers from a trestle that was at this location. Speculation is that slides played a role in burying it as
well".
The new shed is constructed of a series of pre-cast concrete panels, which were manufactured in
Richmond, B.C., and moved to the site by rail.
SNOWSHED
The approaches to the snowshed, 26 metres on one side and 17 metres on the other, are of poured concrete.
The shed, one of the longest on the CP Rail system, has also been designed to accommodate possible electrification
of the rail line. In all, the structure measures 25.5 metres wide by 7.9 metres high.
Mr. Arnold said the key to making the shed work as intended is the realignment of the slide path.
Measuring approximately 80 metres wide and a kilometre long, the path is one of the worst in the area.
CHALLENGE
More than 266,000 cubic metres of earth and rock had to be moved in order to redirect the path over the shed and
away from the Trans-Canada Highway through the park below the rail line.
"Even before we could begin, it took three weeks just to clear the snow and debris from the slide chute",
Mr. Arnold recalled. "The next big challenge was removing a boulder measuring some 20 metres high by 20 metres
wide that was right in the middle of the path".
Over the years the boulder had been deflecting debris coming down the mountainside and spreading it over a wider
area.
The project to redirect the slide path and build a snow and mud shed over th rail line that could withstand the
rigors of nature required more than two years of planning. To accomplish the task with a minimum of disruption to the
environment in the national park, CP Rail also worked with Parks Canada.
"This project will provide greater safety to trains and motorists as well as remove any potential costly
delays", Mr. Arnold said.
This CP Rail News article is copyright
1987 by the Canadian Pacific Railway and is reprinted here with
their permission. All photographs, logos, and trademarks are the property of the Canadian Pacific Railway
Company.
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