CHAPTER 2. SITE INVESTIGATION
Consideration of potential glacial ice runway
glacial ice, and these sites should not be immedi-
sites should be based on a well-established list
ately ruled out. In fact, if the region of desired
of performance needs. Only then can prelimi-
runway location has mild temperatures for any
nary site selection be undertaken. The type of
portion of the summer season, snow is needed for
aircraft available for use, the times of year for
maintenance of the runway. In areas that could
have temperatures above about 10C, particular
operation, the expected life of the facility, the
locations requiring air service support, and the
attention should be paid to features that suggest
volume of personnel and goods needed must
seasonal melting on a regular basis. Examples of
be fully considered. These performance crite-
this might include stream-like features, melt/re-
ria, and perhaps others unique to a particular
freeze glacial ice blisters, plumes of dirt and gravel,
user, will dictate the length, width, elevation,
or "rotted" snow surfaces.
smoothness, bearing capacity, and suitable geo-
Based on historical records, site visits at sev-
graphic setting of the runway. Standard aircraft
eral times of the year over a two-year period
manufacturer 's literature will suggest runway di-
and airphotos, Mellor (1988) selected the gen-
mensions for each model of aircraft, assuming a
eral area of the ablation/accumulation transi-
conventional surface material (paved or rock).
tion zone on the McMurdo Ice Shelf as most
However, since a glacial ice runway will dictate
suitable for a glacial ice runway.
operating at lower levels of friction coefficient,
with possible blowing snow and poor contrast
(visibility) and minimal navigational aids and sup-
PHYSICAL PROPERTIES OF SITES
port equipment (tow vehicles, crash tenders, han-
gars, etc.), it is prudent to plan for the runway to
Following the initial selection of potential
exceed the recommended dimensions by at least
sites, the specific characteristics of each of the
50%.
locations must be determined (for example,
A number of potential sites should be con-
Kovacs and Abele 1977, Mellor and Swithinbank
sidered in the early stages of locating the facil-
1989, DenHartog 1993). This will involve visits
ity. Concurrent investigation of several sites will
to the sites that may require helicopter, small
reduce the possibility of long delays, if undesir-
fixed wing aircraft, or off-road vehicle support.
able features are discovered, and will allow for
Mellor and Swithinbank (1989) completed the
a comparison of the merits and challenges of
early site analysis on the McMurdo Ice Shelf,
certain locations. Rarely will an ideal location
and narrowed down the appropriate region for
be found, and compromise, based on the spe-
a glacial ice runway to the Pegasus site.
cific needs and resources of the facilities users,
will govern the siting of the glacial ice runway.
Ice characteristics
Perhaps the most important aspect of selecting
a glacial ice runway site is to ensure that the ice is
sound and will support the type of aircraft planned
INITIAL SITING
for use on the runway. Information on the subsur-
Initial selection of potential sites in the re-
face ice can be attained using various kinds of
gion of interest for a glacial ice runway, espe-
nonintrusive methods. Penetrating devices like
cially in a remote area, should be accomplished
radar (Arcone et al. 1994) and microwave may be
using aerial photos and Landsat images. For
able to provide key initial information as to the
example, potential sites in Antarctica were re-
ice's integrity. However, ice cores will be needed
viewed by Swithinbank (1989, 1991) using
to augment the output from such devices, and
airphoto libraries. After identification of large
much can be learned through an ice coring pro-
ice expanses, sites will be examined that have
gram in the area where it is most likely the run-
level topography and are several miles distant
way would be situated. Since the runway itself
from tall obstacles (e.g., mountains). The aerial
will cover a large area, cores should be taken over
images should also be scanned for deleterious
a wide range of possible ice types and features at
large-scale topographic features such as cre-
the site. The goal will be to avoid being surprised
vasses or discontinuities in the ice. In some ar-
by a weak ice area or undesirable features after
eas a thin snow cover may exist over sound
construction has begun. Unlike conventional run-
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