CEMP-E
TI 850-02
AFMAN 32-1125(I)
1 MARCH 2000
Ballast
a. Description: Most track in the primary routes has ballast composed of a low density, finely crushed
volcanic material or slag, or cinders mixed with earth. Some stretches of track appear to have no real
ballast section, leaving the track essentially sitting directly on the subgrade.
During recent track work, some new ballast was applied. This ballast is crushed rock of about AREMA 3
or 4 gradation and appears to be good, hard material. However, in most cases, this ballast is only a
surface treatment, helping to fill in cribs (the spaces between the ties) and fill out the shoulders (at the
ends of the ties).
b. General Condition: The cinder/volcanic/earth material seems to drain adequately, but apparently
provides insufficient lateral or longitudinal stability to the track. (See Track Geometry section below).
Additionally, this material is not sufficiently dense and stable to resist washout from heavy rains. (See
Drainage/Subgrade section below).
Drainage/Subgrade
a. Description: While the rainfall in this area of the country is not high, much of the rain comes in short,
heavy periods, resulting in flash floods and washouts. Culverts at the installation are generally large (as
big as 72 in.) and often of double pipe arrangement, not only to accommodate sudden heavy flows, but
also the debris that is swept along by the water.
The track is built on a sandy subgrade, and is generally elevated above surrounding ground level. There
are, however, clay layers near the surface in some locations.
The large, flat areas containing tracks in the classification yard and in the Administration Area do not have
a subdrainage system.
C-13
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