Unitec American Parking Equipment - Manual (Page 23)

Document Number: GC1001 19
Document Title: Unitec APE Gate and Gate Controller for Multi-Lane Applications Installation Guide
2 Merge Zone Loop Guidelines
When queuing (stacking) cars from the WSII/Portal to the tunnel entrance, it is
possible for cars to get out of order in the “merge zone” area from just after the
terminal gates until where the tunnel entry area narrows to a single lane. To stop this,
vehicle detection loops, or merge loops, are installed in the merge area to keep the
gates from opening until the last car is into the single lane.
Install and connect merge loops to the Gate Controller in the following manner.
2.1 Installation of the Merge Zone Loop or Loops
A loop should be placed in the pavement below the gate. This loop is used to detect
the presence of a vehicle, keep the gate from closing on cars, and tell the gate to
close after the car is beyond it.
• The loop should be approximately 2.5 feet long by 6 feet wide to cover the car
lane under the gate arm. The leading edge of the loop should be even with
the gate arm, and the trailing edge of the loop should be 2.5 feet beyond the
gate arm. The loop wire should make 4-5 turns around the pavement saw-cut,
to provide the correct inductance needed for detecting automobiles.
• The loop leads should be twisted 6 turns per foot, from the edge of the loop to
the connections on the X21 terminal strip. These twists are necessary to
minimize interference and prevent false loop detection.
• If multiple gates are installed, the loop frequency setting should alternate on
each adjacent gate so that interference does not occur.
Note:
The American Parking Equipment G89E gate includes some useful loop installation
information included in the documentation included with the gate.
2.1.1 Loop Placement
The merge loop must be positioned so that it can detect a vehicle’s presence before
the vehicle leaves the gate loop. The front edge of the merge loop should be no more
than 9 feet away from the back edge of the gate reset loop to ensure proper detection
of vehicles.