Level Approach
An
ideal design is a slightly inclined approach that does not inhibit the
positioning of trailers, but allows water runoff away from the building
(Figure 1). This also helps prevent the potential of damage to the
building from trailers that are severely angled when positioned by
jockey trucks.
Declined Approach
Declined
approach areas are constructed when the floor of the building is even
with the exterior grade level. To achieve a proper dock height for truck
loading/unloading operations, the approach to the dock needs to be built
incorporating a decline to the building.
There are some issues of concern with a declined approach to the dock.
These include: difficult snow removal, water drainage, buildup of
debris, and high impact forces to the dock. There is also the potential
for serious damage to the building wall from impact by the top of the
trailer. Approaching trucks can generate severe impact forces from only
a short distance. Increased bumper projection or a projected dock must
be provided to avoid building damage.
Special considerations must be made when incorporating other loading
dock equipment with a declined dock approach. Dock seals need to be
tapered to match the angle of the trailer. If the seals are not tapered,
effective sealing will not be accomplished and dock seal damage
is likely. Vehicle restraints must also be projected sufficiently to
ensure proper operation and safety.
Overcoming impact to the building wall is easily accomplished. For new
construction projects, the dock can be projected sufficiently to prevent
the top of the trailer from impacting the building wall.
Required projection is determined based on the percentage
of grade. To calculate the grade, measure the difference in height from
the dock to a fixed point approximately 50' directly out from the dock.
Divide the height difference by the length measured, using inches (eg.
18" difference over 600" distance. 18/600 = .03 x 100 = 3% grade)
Declined approaches should not exceed a
10% grade for proper and efficient dock operations.
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