APPENDIX A
Presence Detection Active Barrier Safety System
[NOTE TO DESIGNER. Include a drawing showing the control switches and control
logic for this scheme. Use Drawings E1.03 and either E1.05 (no queue
preemption) or E1.06 (queue preemption) in the Standard Design or provide new
drawings if the control switches and controls on Drawing E1.03, E1.05, or
E1.06 are modified. If the controls are modified from Drawings E1.03, E1.05,
or E10.6, the following control sequences must also be modified.]
1 PRESENCE DETECTION SAFETY SCHEME FEATURES. Provide the following features
for the Presence Detection Safety Scheme:
1.1 One Active Vehicle Barrier at the end of the Response Zone in each
inbound and each outbound lane.
1.2 Dual phenomenology vehicle presence detectors (VPDs) located in front of
the Stop Line (detectors 1a and 1b), between the Stop Line and the barrier
(detectors 2a and 2b), and immediately after the barrier (detectors 3a and
3b). Presence detectors can be induction loops, IR Break Beams, video motion
sensors, or other suitable technologies capable of sensing vehicle presence.
1.3 Passive barriers on raised islands between each inbound and each
outbound lane. Passive barriers and islands shall extend from just ahead of
the range of VPDs 1a and 1b to just beyond the trailing edge of the range of
VPDs 3a and 3b. See Drawings.
1.4 Passive barrier on a raised median island between the inner most inbound
and outbound lanes. Passive barrier and median island shall extend from the
end of the last Turn-around to either the trailing edge of range of the
inbound VPDs 3a and 3b or the leading edge of the outbound VPDs 1a and 1b,
whichever is further. See Drawings.
1.5 A three light Traffic Signal at each inbound and outbound lane. The
three lights in each Traffic Signal shall be Red-Yellow-Green top to bottom.
The Traffic Signal shall be located 3.5 feet behind the front edge of the
Stop Line as a driver normally approaches the barriers.
1.6 A 2 foot wide Stop Line placed 24 feet in front of the active vehicle
barrier as a driver normally approaches the barrier.
1.7 Actuated Traffic Arm 11.5 feet beyond the front edge of the Stop Line.
Provide an Auto-Test selector switch and Open and Close switches for the ATA
in the Barrier Control Cabinet. In the Auto mode of the selector switch, the
ATA control shall mimic the adjacent active vehicle barrier. In the Test
mode of the selector switch, the ATA shall be controlled by the Open and
Close switches.
1.8 Vehicle presence detection systems to detect queues on any inbound or
outbound lanes in front of the barrier(s). VPDs shall be a minimum of 117
feet in front of the front edge of the Stop Line and shall cover an area the
width of the lane(s) by 50 feet long. Multiple loops may be used to achieve
the 50 foot required length.
1.9 One Master Control Panel, one Guard Booth Control panel for each Guard
Booth, one Overwatch Position Control Panel, and a Local Control Panel for
each barrier along with all control switches and indicating lights as shown
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