TM 5-852-1/AFR 88-19, Volume 1
2
= h /16 can be used as a rough guide (P is in tons and h
for the reduced strength of snow ice, 1 inch of snow ice
is in inches of solid, clear ice). Table 2-1 is a slight
is equivalent to only 1k inch of clear ice. If any
refinement over the above formula for short-term
substantial operation involving loading of floating ice is
loading. Solid, clear, freshwater ice has no air bubbles
contemplated, guidance should be requested from the
that might reduce strength. Ice containing air bubbles
U.S. Army Cold Regions Research and Engineering
("snow ice," often formed by the freezing of water soaked
Laboratory in Hanover, New Hampshire.
snow) is not as strong as clear ice. To account
Table 2-1 Approximate short-term or moving load-carrying capacity of solid, clear, fresh water Ice (see text for snow ice).
Necessary ice thickness (in inches)
at average ambient temperatures for three days
Total weight
Distance between
Type of vehicle
(tons)
32 to 20F
15F and lower
vehicles (ft)
Tracked
6
10
9
50
10
12
11
65
16
16
14
80
20
18
16
80
25
20
18
100
30
22
19
115
40
25
22
130
50
27
25
130
60
30
28
150
Wheeled
2
7
7
50
4
9
8
50
6
12
11
65
8
13
12
105
10
15
14
115
NOTE:
When the air temperature has been 32F or higher for a few days, the ice should be considered unsafe for any
load.
winds that may be concentrated in valley outlets should
2-5.
Wind and wind chill
be considered in site selection. If strong winds are
possible, they may especially affect outdoor activities
In many parts of the Arctic and Subarctic, where
during the colder months. Worker efficiency decreases
pressure gradients tend to be weak and temperature
with lowering of air temperatures (about 2 percent per
inversions are common, surface winds may normally be
degree below 0F), but wind significantly increases this
fairly low. Where pressure gradients are more marked,
effect, as shown by the wind-chill chart, figure 2-9.
however, as in areas near seacoasts, and in and near
Distribution of January wind-chill values in North America
mountains, strong winds may be quite common and wind
is shown in figure 2-10. Information on the effects of
speeds can attain hurricane velocities. For example, a
various levels of wind-chill upon persons working
maximum estimated wind gust in winter of 130 miles per
outdoors is given in table 2-2.
hour has been reported for Kotzebue, Alaska. The
possibility
of
strong
katabatic
2-13
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