APPENDIX A
Presence Detection Active Barrier Safety System
the Open and Close switches on the barrier's Local Control Panel.
Maintenance personnel would also have to block and mark the lane ahead of the
barrier and also lock and tag out certain equipment at the barrier per the
barrier manufacturer's recommendations for the type of maintenance to be
performed.
3 TRAFFIC SIGNAL AND BARRIER CONTROLS.
3.1 EFO MODE OF OPERATION. In the EFO mode of operation with the barrier
open and no vehicles on VPD 1a or 1b, the Traffic Signal shall be Red. If a
vehicle is detected by either VPD 1a or 1b, there shall be a one second delay
and then the Traffic Signal shall change from Red to Green to allow the
vehicle to pass over the barrier. Once the vehicle is detected by either VPD
2a or 2b, the Traffic Signal shall change from Green back to Red. This
operation is similar to Lane Metering on freeway entrances. If a vehicle is
detected by VPD 2a, 2b, 3a, or 3b at the instant a guard activates the
barrier Emergency Fast Operate (EFO) command, the barrier "Close" circuit
shall be suppressed until VPD's 2a, 2b, 3a, and 3b are all clear. Also, if a
guard activates the Emergency Fast Operate (EFO) command and the Traffic
Signal is Green, the Traffic Signal shall change from Green to Red and the
barrier "Close" circuit shall be suppressed until the vehicle is detected by
either VPD 2a or 2b. If the vehicle is detected by VPD 2a or 2b, the
suppression will continue until VPD's 2a, 2b, 3a, and 3b are all clear as
described above. If neither of these conditions exist at the time that a
barrier Emergency Fast Operate (EFO) command is activated, the barrier
"Close" Circuit shall not be suppressed and the barrier shall immediately
close in its emergency fast mode (2 seconds or less). See typical control
schematics on the Drawings.
3.2 [NOTE TO DESIGNER: Delete paragraphs 3.2 and 3.3 if Queue Operation is
not required.] QUEUE OPERATION. If vehicles back up behind the Stop Line
during periods of heavy traffic such that the queue VPD detects a vehicle
continuously for 30 seconds, the Traffic Signal shall go from Lane Metering
operation to Queue operation. In the Queue operation, the Traffic Signal
shall change to Flashing Yellow and vehicles will be allowed to pass over the
barrier without stopping at the Stop Line. The Queue operation shall end
immediately when the Queue VPD does not detect a vehicle. When the Queue
operation ends, the Traffic signal shall change from Flashing Yellow to Solid
Yellow and then to Red and resume Lane Metering operation. The distance
between the Queue VPD and the Stop Line is such that the last vehicle leaving
the Queue VPD will see the Traffic Signal change to Solid Yellow and Red in
time to have to stop at the Stop Line. Since this operation relies on the
vehicles in the queue to stop a threat vehicle, the last vehicle in the queue
must stop at the Stop Line.
3.3 EFO DURING QUEUE OPERATION. If an EFO command is activated from any of
the Control Panels during Queue operation, the Traffic Signal shall go from
Flashing Yellow to Solid Yellow for 4 seconds and then to Solid Red. After
an additional 1 second of Solid Red, the barrier close circuit shall be
energized, provided that there are no vehicles detected on VPD's 2a, 2b, 3a,
or 3b. If a vehicle is detected on any of these VPD's, the barrier close
circuit will be suppressed until all VPD's are clear.
3.4 EFO RESET. After an EFO activation, guards will close all inbound and
outbound lanes. Guards will then activate the EFO Reset switch on the
Master Control Panel to reset EFO, place each barrier's mode switch to the
Test position, open each barrier using the Open switches on the Master
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