TM 5-840-2
CHAPTER 5
OPEN STORAGE
5-1. General.
volume and flow patterns, material accessibility,
and weight requirements of the stored material.
Open storage areas are portions of the depot that
Types of surfaces that are frequently used on
are used for the storage of goods that do not
improved storage areas: rigid pavements, flexible
require extensive protection from the elements.
pavements and roller compacted concrete pave-
They are generally unimproved or semi-improved
ments (RCCP). The choice of type depends upon
areas which do not provide any cover for the
the usage requirements listed above. Rigid pave-
materials stored therein. These areas should be
ment applications such as concrete slabs are dura-
provided with the same access that is given to
ble, long lasting, capable of resisting larger loads,
warehouses and sheds as well as shipping and
and unaffected by the normal range of temperature
receiving facilities that are necessary for open
fluctuation experienced throughout the year. They
storage functioning. For planning purposes, a par-
do require considerable labor in fabrication and are
tial list of materials that may be stored in open
generally the more expensive method of providing
storage can be found in Department of the Army
improved surfacing. Flexible pavements are less
Supply Bulletin SB 740-1.
durable, more sensitive to high temperatures,
a. Improved areas. Open storage areas which
require greater base and subbase preparation,
are the most flexible as storage sites are the
deflect more than rigid pavements under load, and
improved areas. These sites are cleared of vegeta-
in recent years have not provided much of a price
tion, graded, and provided adequate drainage, and
advantage over rigid pavements. For flexible
then given some sort of hard treatment. This allows
pavements, the mechanical handling equipment
the storage of many items that would not be
(MHE) wheel characteristics vary to such an extent
suitable on unimproved areas due to the increased
that for similar load-carrying capacities, different
bearing capacity of the surface and the high level of
vehicles may require different surfacing
control of runoff. Typical materials used to surface
requirements. The wheel loads, number of wheels
the area are concrete slab and asphalt pavement.
per vehicle and their arrangement on the vehicle,
Less suitable materials would be steel mat and
the tire contact pressure, and the tire contact area
crushed and rolled stone. These latter methods of
all determine the pavement loading and
improving the surface will not allow maximum
consequently its thickness. Because of this variation
bearing capacities on the ground surface.
in pavement requirements, the engineering
b. Semi-improved areas. These areas are similar
construction and maintenance effort may be several
to improved areas in that they are graded and
times greater for one vehicle than for another with
drained, but they are not provided with a hard top
equal load-carrying capability.
surface. The bearing capacity of semi-improved
b. Traffic volume and flow patterns. Traffic vol-
areas will change with the moisture content of the
ume is a primary consideration in the selection of
soil and in wet conditions will not bear as heavy a
the type of surfacing and its required thickness. It
load as in dry conditions.
is essential that an adequate study be made to
c. Unimproved areas. Surfaces that have not
determine the number of passes and the operational
been graded, drained, or hard-surfaced are classi-
flow patterns of each vehicle under consideration
fied as unimproved. Irregular surface contours do
so that a reasonable design volume for a particular
not allow uniform storage heights, and lack of
facility and vehicle can be selected. The material
grading and drainage tends to promote localized
selectivity will also affect the type and thickness of
areas of water ponding and to reduce bearing
the pavement. Selectivity involves the relative ease
capacity due to saturation of the soil. This is the
with which material can be located and removed
least desirable form of open storage area since it
from the storage area. Items stacked such that
does not promote dense storage practices nor does
other items must be moved in order to access the
it provide for acceptable access to the storage area.
needed item will require a number of vehicle passes
dependent on the size and number of items to be
5-2. Surfacing requirements.
moved. In this situation, the expected life of the
a. Choice of pavement type. The factors that
pavement would be shortened due to the increased
affect the surfacing requirements of improved open
number of passes.
storage areas include vehicle characteristics, traffic
5-1
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