Vol. 17 No. 5
May, 1987
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Stay Safe in 87
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Vent Shaft Breaks Through to Tunnel
Inspectors check the ventilation shaft.
After 22 months of drilling and blasting, work crews broke through the bottom of a
349-metre-deep ventilation shaft in Rogers Pass, B.C., 1 Apr 1987, linking it with the
Mount Macdonald tunnel.
The 8.5-metre-diameter shaft is the key component to a ventilation system that is designed to purge the
14.6-kilometre railway tunnel of locomotive exhaust. The system is the only one of its kind in the
Western Hemisphere.
The ventilation system is important to the operation of the tunnel because exhaust fumes from one train must be
purged quickly before the next train arrives. If the ventilation system works slowly, fewer trains will be able to
use the tunnel, resulting in a capacity problem that the Rogers Pass Project was designed to solve.
In effect, the ventilation shaft bisects the tunnel to permit twice the train frequency that would otherwise have
existed.
The mid-tunnel facility allows the eastern portion of the tunnel to be purged while a train is passing
through the western portion.
It will operate this way:
As the train approaches the tunnel's east portal, a specially-designed portal door will open
automatically while a mid-tunneldoor will remain closed. Fresh air will be forced down the eastern
section of the 366-metre vent shaft and along the length of the train to cool the locomotives and
force exhaust fumes out the east portal.
When a train reaches the middle of the tunnel, the mid-tunnel door will open and when the rear of the
train has passed the middle of the tunnel, it will close. Air will then be forced along the train and exhausted up
the western section of the vent shaft.
The power and fan systems for the ventilation system will be housed in a surface building near the top of the shaft.
When the project is completed, the railway will be able to run a train through the tunnel every
half-hour.
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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