Vehicle Detection Systems

There are a number of ways to detect vehicles in a Drive-Thru lane including (1) a pressure hose (2) ultra-sonic sensor or (3) a magnetic, inductive loop. Magnetic, inductive loop technology is the most reliable for a Drive-Thru lane; it is the method of vehicle detection used for most traffic signals. 

A loop detection system consists of primary components:

  • a loop: (1)“pre-formed” for new construction or (2)“saw-cut” for existing locations 
  • (3)an extension cable to connect to the building and
  • (4) a vehicle detector box.

The vehicle detector box used in a restaurant Drive Thru lane can be connected to a number of devices including a timer system, an automatic greeter or directly to the communication system.

How the magnetic, inductive loop works:

The pre-formed or saw-cut loop is buried 2 inches below the surface in the pavement of the traffic lane.  The ‘loop’ is a continuous wire that is ‘looped’ in pavement in a rectangular fashion and enters and exits at the same point (See diagram)

    HINT: Install the loop a few car spaces before the actual speaker post or communication system. This will allow extra time for the crew to react and be ready for the customer.



The two ends of the loop wire are connected to the extension cable in the speaker post or menu board.  The extension cable is run into the building to be connected to the vehicle detection device.  The vehicle detection device powers the loop causing a magnetic field in the loop area.  A constant frequency is established when no vehicle is present which the detection device monitors.  When a large metal object, such as a car, moves over the loop, the frequency increases and is sensed by the detection device.  The detection device triggers the connected device such as a gate, a traffic signal, an automatic ‘greeter’, a timer or an audio intercom system.

Attention to detail is needed when installing or ‘trouble shooting’ an inductive, magnetic loop.  The loop must be buried correctly in the concrete or asphalt to sense compact cars as well as larger vehicles.  Lower riding vehicles are easier to sense than large SUV type vehicles whose undercarriage is much higher from the pavement.

Mainstreet Menu Systems/Howard Company offers both types of inductive, magnetic loops (Pre-formed or Saw-cut) including the 100 feet of extension cable and the vehicle detector box.

1) Pre-formed loop Assembly: A pre-formed loop is 3 to 5 turns of wire encased in a PVC pipe for use in new construction before the pavement is installed.  The wire is encased in the PVC to hold the loop’s shape and to protect the wire from damage while the pavement is setting. To see installation information click here...



2) Saw-cut loop Assembly: A saw-cut loop is used when the pavement is already in place.  The installation requires:

  • cutting a loop with a concrete saw
  • laying the wire in the slot 
  • pressing a polyfoam  backing in the slot to keep the wire compacted and then 
  • filling the slot with a sealant or street bond to fill the slot and protect the wire.  To see installation information click here...



Other items needed:

3. Extension Cable: The extension cable is used to extend the pre-formed or saw-cut loop to the vehicle detection device located indoors.  The extension cable must be soldered to the loop wires for a good connection.  The distance from the loop to the detector device can be up to 300 feet if done properly.  100 feet of extension cable is included with both the pre-formed or saw-cut assembly.

4. Vehicle Detector Box: The Vehicle detector or ‘black box’ is normally located inside the restaurant for easy access and troubleshooting.  As mentioned, the output from the vehicle detector box can trigger a number of different devices. To view an instruction sheet on this click here....



For more information or to place an order, please call our drive-thru communications specialist directly at 800-782-6222.


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