Download and the Alaska Highway - Highways and Public Works

Permafrost Research in the Yukon
The Yukon government maintains the Yukon portion of
the Alaska Highway although the United States is also
concerned with the level of service on their only land
link to Alaska. Up to 85 per cent of those who travel
the northern section of the highway are American. To
improve service, the Yukon Department of Highways
& Public Works is working with the State of Alaska,
the U.S. Federal Highways Administration, Transport
Canada, Laval University, and the Alaska University
Transportation Centre on a major permafrost research
project near Beaver Creek, Yukon.
The ice-rich permafrost in this area causes dramatic
settlements in the road when it melts. The project
aims to test several techniques which are designed to
prevent permafrost thawing including: air convection
embankments, built out of 150-300 mm diameter rock;
heat drains, which involve ventilation pipes and a porous
layer of geocomposite; snow sheds; longitudinal air
ducts; light-coloured aggregate for road surfacing and
modified snow plowing techniques. The principle idea is
to prevent the permafrost from melting by increasing the
amount of cold air that enters the embankment during
the winter, or by reducing the amount of solar radiation
that is absorbed in the summer. The goal is to develop
road designs that are practical and cost effective.
and the Alaska Highway
Drive Carefully!
Fortunately much of the Yukon highway system is
presently unaffected by degrading permafrost, however,
north of Destruction Bay you can expect to encounter
dips and bumps in the road surface as well as potholes,
longitudinal cracks, and gravel patches. The more severe
bumps are generally marked with red flags, so prepare
to slow down where you see these markers. Also watch
out for our repair and maintenance crews who work on
the road to keep the highway in a safe driving condition.
Please drive appropriately to road conditions and stay
alert for vehicles slowing down ahead of you. Build a
little extra time into your trip and stop occasionally at
the highway pull-offs to take a break and enjoy the
spectacular scenery!
Road Report
For more information on road conditions in the
Yukon contact:
Yukon Road Report (24 hours/day)
Dial 511 if you are within Yukon or visit our
website at www.511yukon.ca
References
1. Larsen, P. & Goldsmith, S. (2007). How Much Might
Climate Change Add to Future Costs for Public Infrastructure?
UA Research Summary No. 8. Institute of Social and
Economic Research. University of Alaska Anchorage.
Retrieved on 29/02/2008 from:
http://www.iser.uaa.alaska.edu/Publications/Juneclimatefinal.pdf
2. Natural Resources Canada:
http://gsc.nrcan.gc.ca/permafrost/index_e.php
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The Alaska Highway is Sinking!
The 2,647 kilometre (1,645 mile) Alaska Highway runs
from Dawson Creek, British Columbia to Fairbanks,
Eagle Plains
Alaska and is built in zones of both continuous
5
and discontinuous permafrost. Problems related to
melting permafrost are rare along the highwayPesouth
River
el
of Whitehorse, however, northwards from Whitehorse
towards Haines Junction permafrost related settlements
of the highway are more frequent. The 220 km (137
mile) stretch of highway from Destruction Bay on into
Alaska is underlain by extensive areas of warm icerich permafrost which continues to melt resulting in an
uneven, “roller coaster” road surface as well as cracks,
potholes, and frequent gravel patches.
Exposed permafrost in Katherine River Valley, Torngat Mountains,
Labrador. Photographer: Van Kranendonk, M. J., photo # A92S0044
What is Permafrost?
Visible ice lens and melt water from disturbed permafrost.
Courtesy of Natural Resources Canada, photo # 2000-168.
Permafrost and Climate Change
Permafrost and Infrastructure
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Yu
Permafrost is defined as ground that remains at or
below 0° Celsius (32° Fahrenheit) for two or more
years. There are two permafrost zones: continuous
permafrost and discontinuous permafrost. In the
continuous permafrost zone, permafrost lies beneath
the entire surface except beneath large rivers and deep
lakes. In the discontinuous permafrost zone, permafrost
lies beneath 10 to 90 per cent of the surface. The
temperature and thickness of permafrost can range
from –10° C/14°F or lower and very thick (up to 1400
m/4593 feet) in the Arctic, to warm (one or two degrees
below the melting point) and thin (up to 150 m/492 feet)
in the subarctic.
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Permafrost Affected Areas of the
Dawson City
Alaska Highway
within Yukon
Temperatures have risen sharply in recent decades over
most of the Arctic and sub-arctic region, especially in
winter. Over the next 100 years the Intergovernmental
Panel on Climate Change (IPCC) is predicting an
increase in the average global temperature of 1.4°C to
5.8°C (35°F to 42°F). Since the average annual near
ground temperature in most of the Southern Yukon is
between 0 and -2°C (32°F and 28°F) this warming is
expected to have a significant impact on the stability of
permafrost.
Despite its name, permafrost is characterized to a
certain extent by instability. Permafrost is covered by
a relatively shallow “active layer” which freezes in the
winter and thaws in the summer. However, when the
permafrost is altered by construction or climate change,
the active layer can become much deeper and not refreeze, even in the coldest winters. When roads, bridges,
or buildings are built on top of this melting permafrost,
they too can sink, causing the infrastructure to become
unstable.
A new study by the Institute of Social and Economic
Research at the University of Alaska Anchorage has
concluded that climate change could add an extra
$6.1 billion to the future maintenance and replacement
cost of public infrastructure between now and 2030 in
Alaska alone (Larsen & Goldsmith, 2007). Therefore,
it is essential to develop a sound understanding of the
impact of climate change on infrastructure in permafrost
regions and to develop appropriate adaptive techniques
and practices to mitigate the impacts.
To protect roads from permafrost degradation scientists
and engineers have been developing ways to prevent
the permafrost beneath the road foundation from
warming, thus keeping the permafrost layer in its more
stable frozen state. In the absence of such engineered
solutions, intensive maintenance efforts are required to
keep roads on ice-rich permafrost in a reasonable state
of repair.
Stewart
Crossing
ALASKA
Yu
k
on
River
Pelly
Crossing
Beaver Creek
YUKON
Carmacks
1
Burwash Landing
Destruction Bay
1
Haines
Junction
Champagne
Whitehorse
LEGEND
1
Alaska Highway
Permafrost Affected Areas
BRITISH COLUMBIA
Pe
l