has not exceeded 3.66 m (144 inches). A minimum
height of 711 mm (28 inches) is required. Consult
manufacturer's literature for barrier heights.
The table below shows typical performance levels as
a function of barrier height.
(Barrier Height
Typical
Above Road
Average Barrier
Performance
Surface mm (in)
Height (mm) (in)
Level
787-1016
914
L3.0,
K12
(31-40)
(36)
L3.0,
K12
610-914
762
L2.0, K4 and varied
lower levels
(24-36)
(30)
L2.0, K4 and varied
lower levels)
There are no known barriers capable of supporting
loads larger than those indicated here and which
will meet all other requirements found within this
guide specification. These load limits are adequate
for normal commercial truck traffic but will not
support the Army's Heavy Equipment Transporter (HET)
or similar vehicle. Overall design consideration
must include providing alternate access for these
vehicles if they have a valid reason for entering
the secured area.
Federal and/or state EPA regulations may require
that an oil/water separator be installed in the pit
drainage system to ensure capture of any hydraulic
fluid that may leak out of the system. If pit/vault
type construction is required provisions will be
made for drainage and connection to storm drainage
system, or if no storm drain exists, a self-priming
submersible sump pump of adequate capacity will be
specified.
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When in the raised position, the total retractable barrier heights shall be
no less than [_____] mm inches above the roadway surface and shall be
[_____] mm inches wide. When in the lowered position, the retractable
barrier shall extend no more than 16 mm 5/8 inch above the roadway surface.
Retractable barriers in the lowered position shall be capable of
supporting a 142 kN 32,000 pound axle load or a 71 kN 16,000 pound wheel
load. Design for this load shall be in accordance with AASHTO HB-17.
2.1.1
Powered Retractable Barrier
**************************************************************************
NOTE: Based on peak hourly volumes, fill in number
of cycles per hour that the barrier will be required
to function (maximum 300 complete up/down cycles per
hour).
**************************************************************************
The retractable barrier shall be capable of [_____] complete up/down cycles
per hour. The retractable barrier motion shall be instantly reversible and
shall be capable of raising the barrier from the lowered position to the
raised position within 8 seconds during normal use, and within 2 seconds
SECTION 02840
Page 10
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