Driveway Gate Vehicle Detection - Loop Detectors & Loops Overview

Vehicle detector loops are like large metal detectors which detect all metal vehicles including bicycles. Loops in gate systems need to be installed correctly and are one of the most common causes of automation system failure. The most common type of failure is due to leakage to ground which occurs when moisture penetrates the insulation of the wire. Poorly spliced loop wire or splices which are not watertight are other common points of loop failure. An indication your EXIT loop has failed is when the gate will not close. See our Loop Troubleshooting Article for more information.

There are 2 basic components to this type of driveway vehicle detection; the Loop Detector & the Loop.

Loop Detectors:

Loop Detectors are the "brains" of the system. They are control module components which are installed on the gate operator control or circuit board and operate in tandem with the loop. Loop Detectors control what type of actions are taken when the presence of a vehicle detected. There are 2 types of installations methods; Plug-in and Hard-Wired. Some gate operators have built in sockets to accept loop detectors (plug-in type) while some models require the detector to be wired in using a harness and connectors.

There are 2 Basic Types of Loops:

Saw-Cut or Cut-In Loop - For installation in existing roadway applications. The loop is installed in a groove cut into the existing pavement. Saw-Cut Loops are available as Cut-In Loop Wire for custom sized loops or Preformed Loops which come pre-sized with differing lead-in wire lengths for easy installation. All Saw-Cut Loops need to be sealed with Loop Sealant.

Direct Burial or Pave-Over Loop - For installation in a concrete pour, gravel road, under asphalt and under pavers. The loop is laid on the substrate and the surface material is applied over the loop. Direct Burial Loops are Preformed and available in many sizes and lead-in lengths.

Both types of loops are available as Preformed Loops which include the wire already cut to length, twisted, and inside of flexible conduit or a protective sheath for the sensing portion of the loop. In addition, Preformed Loops are available in a variety of lead-in wire lengths which connects the loop to the loop detector.

Probe or Wand Style Vehicle Sensor:

These self-contained types of detectors are a good choice when a standard loop is not feasible. They usually consist of a control module, probe section and a lead-in wire. The probe section is buried a few inches below grade beside the driveway. A Probe Style Vehicle Sensor Should ONLY be used as an Exit Device.

• Exit Loops - Exit Loops automatically open the gate when a vehicle drives over them. Typically placed inside the property so when a vehicle is exiting, the gate will automatically open.
• Safety or Reversing Loops - Safety Loops are used to prevent a gate from closing on a vehicle. Two loops can be wired to one detector which is frequently the case with Safety Loops. Safety Loops are placed in front and behind the gate.
• Shadow Loops - Shadow Loops are used in swing gate applications and are placed inside the swing area of the gate. This loop is only active when the gate is in the full open position and prevents the gate from closing if there is a vehicle present.

Commercial Loop Applications:

• Close Loop - Close Loops are used in barrier operator applications. This loop is placed directly under the arm of the operator. When the vehicle clears the loop, the arm automatically lowers.
• Arming Loop - Arming Loops are used to control access to a site. The vehicle must drive onto the arming loop before using an access device such as a transmitter or card.