Drive-Thru Director Buried Vehicle Detector Expectations
Use this guide when implementing Drive thru director with a preexisting concrete or asphalt drive-thru.
Note
This guide is not a manufacturer-approved installation guide and is only offered as an overview of expectations. Prior to installation, consult the instructions provided by the supplier or manufacturer of the in-restaurant audio and/or timer system. Failure to follow manufacturer-established instructions may void available warranties.
DTD Buried Vehicle Detectors - Helpful Information
Note these key points about vehicle detection systems:
The DTD detects the front axle of a vehicle.
Cabling is placed in the drive-thru in the shape of a rectangle with 45° corners.
Chalk marks indicate the exact location, size of the rectangle, and the corner angles.
The short edges of the rectangle run parallel to the building while the long edges run perpendicular to the building and span the drive-thru.
The maximum vehicle detection height is approximately 2/3 the length of the short-side of the rectangle.
The rear edge of the rectangle is placed ahead of the midpoint of the Menu Board Speaker Post or Window area.
The vehicle detection system should not cross any embedded concrete controller expansion joint.
Metal objects located within a 3' perimeter of the vehicle detection system could potentially disturb the system's magnetic field, create interference, and reduce the field of detection.
Use a continuous piece of un-spliced cabling. The wiring is inserted into the rectangular groove and is looped around the rectangle a total of six times.
During installation, avoid damaging the protective, insulated sheath of the cabling—cuts or abrasions can allow moisture to enter the cabling, causing the vehicle detection system to malfunction.
Keep the working area clean and ensure moisture or sand does not enter the rectangular groove while installing the cabling.
Repair preexisting cracks in the drive-thru prior to installing a vehicle detection system.
Tools and Materials
Below is a list of tools and materials typically required before and during the installation process:
Marking chalk
Measuring tape
Multimeter
Blunt, wooden dowel
Type #18 AWG XLPE cable, 100' (7.3 m)
S/G foam tubing, 3' (0.9 m)
Concrete-cutting saw
Concrete and mortar-repair sealant (Quikrete Hydraulic Water-Stop Cement or equivalent)
Caution
Never use hard-setting epoxies.
Site Survey
Consider these questions during a site survey of a site with a preexisting asphalt or concrete drive-thru:
Was a vehicle detection system previously installed?
If yes, what type of installation is it?
Is the vehicle detection system active?
Installation Types, Locations, and Statuses
There are two main types of installations for pre-formed installations:
Saw-Cut: indicated by visible cuts in the asphalt or concrete of the drive-thru. The cuts form the shape of a rectangle and is where the cabling for the vehicle detection loop is inserted.
Pre-Formed: set in place prior to paving the drive-thru. To detect a pre-formed installation, carefully scan the drive-thru areas listed above for cabling leading into the Restaurant.
Previously installed vehicle detection systems are typically installed in the following locations:
Menu Board(s)
Pay Window
Pickup Window
Using a multimeter, determine the status of previously installed vehicle detection system prior to installation. There are three (3) possible statuses:
Active: a vehicle detection system is attached to a power source. Deactivate the preexisting system before replacing with the new one.
Deactivate Preexisting Systems provides additional information about the deactivation process.
Inactive: a vehicle detection system is not attached to a power source. Verify that the previously installed vehicle detection system is inactive before continuing.
Clean: sites without a previously installed saw-cut or pre-formed vehicle detection system are considered clean installations.
Deactivate Preexisting Systems
To verify that the preexisting vehicle detection system is deactivated:
The vehicle detection system is not attached to a power source.
The preexisting vehicle detection system is inoperable—it is suggested to cut the cabling of the preexisting system in several places so that it does not create interference with the new installation.
Measurement and Placement
Measurement and placement is important when installing a drive-thru vehicle detection system. This technology utilizes equipment that measures electrical fluctuations and is highly sensitive to interference.
The following materials are used to measure and mark the placement of the vehicle detection system:
Marking chalk
Measuring tape
Recommended Measurements and Placement
Listed below are the recommended measurements and placements for the vehicle detection system installation:
The dimensions of the rectangle are 60" (152.4 cm) by 18" (45 cm) with 45° cuts at each of the four corners.
The short sides of the rectangle run parallel with the curbing and measures 18" (45 cm).
The long sides of the rectangle run perpendicular to the cubing, spanning the drive-thru, and measures 60" across.
Each corner of the rectangle has a 45° cut to prevent cable damage.
The rectangle is placed approximately 12—18' (30—48 cm) from the edge of the curbing.
The rear edge of the rectangle is placed approximately 12—24" (30—61 cm) forward of the midpoint of the Menu Board Speaker Post or Window area.
A lead wire runs from a corner of the rectangle nearest the Restaurant through which the cabling is routed through a conduit into the building.
Note
It is recommended to mark measurements and placements with chalk.
Avoid Interference
To avoid interference, provide a perimeter of 3' (0.91 m) around and under the installation area. Confirm that the installation area is free from:
Wire screen
Reinforcing bars
Electrical cables
Metal objects*
Caution
Metal objects located within the perimeter could potentially disturb the magnetic field, create interference, and reduce the field of detection.
Drive-Thru Detector Procedural Overview.
At the install location of the Drive-Thru Detector, verify the rectangular chalk outline measurements and placements.
Following the chalk outlines, cut into the pavement using a blade that cuts approximately 0.25" (0.64 cm) wide and 1.50—2.25" (3.81—5.72 cm) deep.
At each of the four corners of the chalked outline, cut along the marked 45° angles.
From the corner of the rectangle nearest to the curbing and towards the site, cut a lead-wire groove with a blade that cuts approximately 0.25" (0.64 cm) wide and 1" (2.54 cm) deep.
Use the grooves—which act as a conduit to the building—to route the cabling.
Clear the rectangle of debris using compressed air and allow to fully dry.
From the newly-cut rectangular grooves, lay the lead-wire cabling along the groove.
At each corner of the rectangle, follow the 45° angle when laying the cabling.
Following the length of the cabling in the pavement, use a wooden dowel to press the cabling into the bottom of the groove.
In the grooved pavement, insert 3" length of evenly-spaced foam tubing over the cabling holding it in place.
At the end of the cabling, cut the remaining wire into a length equal to the length of the lead-wire groove.
Twist the two ends of the cable together, turning five (5) times per foot.
Test the insulation resistance and DC continuity resistance of the cabling.
Note
If the DC resistance is greater than 3 ohms, or the insulation resistance to ground is less than 100 megohms, the cabling is damaged and the entire installation must be replaced.
Fill the rectangular groove and lead-wire area with sealant fully covering tubing and cabling—never use hard-setting epoxies.
Solder and insulate all connections to the lead-wires.
Retest cabling to confirm proper readings.
Reference Images
These images are not drawn to scale and are offered only as a visual overview.
Approximate Placement
Approximate Measurements
