When vehicle detection technology alerts your staff that a customer has arrived at your order point, it’s a key moment for fast drive thru service. Understanding the technology options available, and correct installation techniques, can help you make better decisions for your specific drive thru situation.
“Highmark provides alternatives so customers can choose their best option,” explains Christian Gonzales, Vice President of Technology at Highmark. “Having helped customers design and select equipment for more than 15 years, I love helping them get the best bang for their buck. It’s important they understand their options so that they are satisfied with their choice.”
Our customers have been telling us that the demand for drive thru service has tripled or quadrupled from pre-covid levels. This means more and more is expected from vehicle detection systems. To ensure customer success, we want to help you understand the differences in the options available and how they perform under different conditions.
The Mechanics of Vehicle Detection
The industry standard is a tried-and-true solution which involves installing a vehicle detection loop made of an 80-strand, flexible, grounding wire. This wire is wrapped around within a 5-foot x 18-inch, 2 1/3-inch deep sawcut in the pavement. The wire is then run into the building and connected to a detection device. The current that runs through the loop creates a magnetic field which is broken when a car drives over the loop, notifying the detector inside the building that a car is present, which generates a “ding” in the headset. When the vehicle moves forward, the magnetic field is restored. Detection loops are most often installed at order points and pickup windows.
Installation is Key
How the drive thru detection loop is installed is critical to ensure good performance, durability, and a long lifespan. Highmark technicians drill a one-inch hole at each corner of the sawcut to avoid a hard 90-degree turn. Rounding out the turn prevents nicks in the wire, which can cause inaccurate readings. We place a 1/4 inch, open-cell, foam backer rod on top of the wire to cushion it and keep the loop in place so it doesn’t float up. We then apply a sealant which passes through the porous backer rod to secure the wire into the ground and help protect the loop from water, heat, dirt, abrasion, oil, and gas. We leave 1/16th inch of space at the top of the sawcut to minimize the risk of a snowplow pulling the loop out of the ground – yes, we try to think of everything! When we’re installing into a new surface, whether concrete or asphalt, we finish the sawcut with a similar material as the surface.
With good installation, vehicle detection loops can serve your drive thru for years. Some of our clients have detection loops that were installed 15 years ago that are still working great. Loops can be installed in either concrete or asphalt but are less likely to have issues in concrete. Poured correctly and under the right conditions, concrete is generally less likely to crack than asphalt and is less vulnerable to spidering/crumbling, wear, and damage from vehicles and weather. Fissures, cracks, or expansion joints in concrete need to be avoided.
We sometimes find that existing asphalt has not been compacted properly or has not been poured to a depth sufficient for the cut required. It may also contain too much pitch, or tar. In this case, it can tend to melt, allowing for tire tracks and other damage to the asphalt, which limits the life of a sawcut. Nonetheless, there’s a lot of asphalt out there since it is less expensive than concrete and can be installed or patched in a broader range of weather conditions. Highmark always looks for and informs the customer of solutions to make a sawcut work., including pouring a 6-foot-wide asphalt strip or patch, into which we can install the sawcut loop.
Traditional Sawcut Loop Alternatives
Winter weather poses the greatest risks for drive thru detection loop failure and it’s when they most often happen. Snow, rain, and low temperatures can short out the loop, create fissures in the wire, or cause other deterioration. Installations and repairs are most challenging during these conditions. We cannot install when there is snow on the surface, and sealant will not set up properly in the rain or in temperatures below 40oF. When repairs can’t wait for better weather, there are alternatives to a traditional sawcut detection loop – a prefabricated detection loop and sonar/sodar technology.
A prefab detection loop, encased in a PVC conduit, can be installed when weather or circumstances don’t allow traditional sawcut loop installation or repair. Using the encased loop eliminates the need for sealant, which won’t set up or seal properly if temperatures are too low. The PVC conduit requires a 1-inch wide cut and is elevated to keep it off the bottom of the concrete or asphalt, while at the optimum height to communicate with the sensor. The surface is cored, the loop placed in the ground, then backfilled with the applicable surface material. This prefab loop is usually chosen for installation during new construction. The coring option is less popular than a traditional sawcut loop because the wide cut is much more conspicuous, and more costly than the traditional sawcut, by approximately 50%, but can be done in colder conditions than a sawcut. A cored, prefab installation requires the drive thru area to be closed longer than during traditional sawcut installation, depending on the curing time needed for the backfill material. Even though the process takes a little longer to complete, the prefab is likely to last longer than a cold weather traditional sawcut.
Sometimes an in-ground loop installation or repair is not possible due to weather, surface material or its condition, or even restrictions imposed by a landlord or municipality. In these cases, Sonar – also referred to as Sodar – may be the solution. This drive thru technology uses a small, powered box which has its own relay, mounted 18 inches off the ground directly on a wall, order point, or even a window. Six to eight sensors send out ultrasonic clicks that can reach eight to a maximum of twelve feet. These hit the vehicle and bounce back, triggering the detector and notifying that a car is present.
The downside to this equipment is that rain, snow, dust, and even gusty winds can sometimes trigger the detection function. So, this solution works best in drier climates or where there are canopies that offer some protection – banks, for example. This system of vehicle detection is sometimes used as a temporary fix, but some customers prefer it as a new drive thru solution because it is easily accessible and therefore easier to repair and replace than in-ground vehicle detection loops. Initial installation requires only about 1 ½ hours. The cost of this system is similar to a sawcut loop, especially if power is already available at the installation point. Highmark’s experience is that current sonar options are about 90-95% as effective as an in-ground detection.
Give us a call to discuss your vehicle detection needs and we’ll find the perfect and most cost-effective solution to keep your business moving.