move and store material are affected by some limiting
factors. These factors are
l
l
l
the dimension of the pallet or load to be handled,
the dimensions of the MHE to move the pallets,
and
the spacing between support columns and
overhead clearances.
In general, utilization of floor area is maximized by
minimizing aisle spare. Aisle space can be minimized
by using modem narrow aisle storage equipment and
storing material in depth when possible. An example
of depth-type storage are those materials that are
inventoried in multiple pallet quantities. See figure 2-3
for an example of storing material in depth. In this
example, the different categories of palletized material
in each row are identified by letters.
Utilization of Building Clear Height
The term clear height is often confusing when
dealing with architects or engineneers. It can mean the
height from the floor to the bottom of the roof or to the
bottom of the beams. In material handling, “clear
height” means the height under all lighting, heating, and
other overhead obstructions. Clear height is the
available effective height for storage space that is below
all necessary clearances. The overhead clearance
required below the sprinkler system is at least 18 inches
for stacks up to 15 feet. This clearance must be at least
36 inches for stacks higher than 15 feet. All overhead
obstructions must be 10 inches above the highest
equipment clearance level.
The utilization of clear height is affected by the
stackability of the material, storage space, MHE, and
floor-load limit. When pallet racks are used to achieve
storage height, the stackability of material is not critical.
When using floor stacked bulk storage, the stackability
and instability of material directly affect the height of
storage. Using storage aids such as pallet frames will
permit load stacking and provide protection to the
material.
Aisles
The preplanning of the aisles in the layout must be
done before placing material in storage. Aisle layout is
determined by the structure of the building, quantity,
nature, and activity of the material to be stored. The
aisle should be wide enough for maneuvering the type
of MHE to be used. The aisle in bins and shelving areas
should be wide enough for stock selector trucks.
Normally, this requires an aisle of 30 to 36 inches in
width. The aisles should provide a straight, clear, and
unobstructed passageway. To determine the width of
the aisles, use the measurement of the turning radius of
the MHE.
The working aisles are used whenever material is
placed into or removed from storage. The two types of
working aisles are the transportation aisles and the cross
aisles. The transportation aisles run the length of the
building. The cross aisles run the width of the building.
Depending on the activity or operations, most
warehouses require two transportation aisles. The
aisles should be wide enough to permit two-way traffic
for the MHE being used in the area.
Personnel aisles are those used as pedestrians routes
only to provide access to doors or other areas. Having
this type of aisle should be held to a minimum. Use the
working aisles also as pedestrian routes if traffic and
safety permits.
Figure 2-3.-Storing palletized material in depth.
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