knew that a hostile unit were positioned so that it posed a threat to
rail operations in a certain area, you would select, if possible, a
rail line that would avoid that area.
After the primary rail lines have been selected, alternative
lines should be chosen, in case the others are cut by enemy action,
tied up by a railway accident, or impaired by washouts, landslides,
or floods.
1.3. TECHNICAL ASPECTS
Because operating a railway is a highly technical business, a
great deal of thought must be given to the technical aspects of
existing rail lines and facilities if rail operations are to be
successful.
Some of the most important technical characteristics,
both desirable and undesirable, are described in the following
subparagraphs.
a. Classification of railways. Railways are classified according
to their gage--the distance between the heads of the parallel rails,
measured five-eighths-inch below the top of the rails.
This
measurement is shown by the broken line
in the inserted sketch.
The general
gage
classifications
are
standard,
broad, narrow, and meter. Approximately
60 percent of the railway mileage in the
world is standard gage, 56 1/2 inches
wide.
Broad-gage railways are 66, 63, and 60 inches wide; narrow-
gage railways are 42 and 36 inches and narrower widths; and meter-
gage railways are 39 3/8 inches wide.
For defense, some countries
construct railways with a different gage from that used by
neighboring countries.
Rail equipment built for one gage does not
operate on other gages.
Track gages vary within a country or area, from country to
country, and from continent to continent; table I presents the track
gages found in principal countries and regions of the world.
b. Desirable physical characteristics.
The railway system in a
theater of operations may be large enough and complex enough to
afford a choice of the part or parts to be used.
Certain physical
characteristics are desirable and must be examined, because they
influence the decision in selecting one railroad instead of another.
(1) Adequate yards, terminals, and shop facilities.
A railway
car
normally spends at least 50 percent of its life
in either
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