RFIDJournal.com’s Best of 2023: How to Track Vehicles

RFID can enable entities ranging from gated communities to car washes and tolling companies to automate vehicle identification, but it helps to keep some simple points in mind.
Published: December 28, 2023

Editor’s note: As we get toward the end of 2023, RFIDJournal.com is looking back at some of the top stories that we published in the last year.

Vehicles are currently being identified for a wide variety of applications, with the help of radio frequency identification (RFID) tags applied to windshields.

In fact, a single car could have as many as three passive UHF RFID tags tracking it for different purposes: opening the gate at a private community or office lot, capturing payment information at toll roads and enabling the driver’s custom choice of services at their local car wash. The use of RFID has been expanding at varying rates among use cases, based on a single key benefit: identifying a car with a relatively lost-cost tag on the windshield.

Colynn Black

Colynn Black

Road tolling is often still conducted with proprietary RFID systems, such as the technology used for E-ZPass in the Northeast Corridor. However, passive UHF RFID tags’ universal protocol (ISO 18000-6B or 6C) for road tolling can operate in this application.

Technology improvements throughout the past decade mean tags can be read at high speeds, and with the sensitivity required from an overhead highway antenna—even during high traffic periods, in bad weather and with the high presence of metal within luxury vehicle windshields.

Although it’s still in its early days, the use of the standard ISO protocol for passive UHF RFID for tolling is being tested or deployed among some large tolling companies, according to Colynn Black, Metalcraft‘s RFID business-development director. RFID chips built into tags are becoming more sensitive and smaller, he says, while the tags are becoming more cost-effective than proprietary versions.

Car washes commonly adopt one of two recognition technologies so that customers can be recognized upon arrival and receive service according to an account they have set up. Either RFID or optical license plate recognition (LPR) can identify a car, with software storing a vehicle’s details, such as whether the owner is a gold or silver member, as well as whether they need a wash and wax or some other extra service.

“As you pull in,” Black says, “it triggers that, and you get in the cycle and it gives you, for example, the silver wash if that’s what you signed up for.” The driver would then be billed automatically.

Optimizing RFID Readers

The goal, Black says, is to identify each vehicle as it pulls up to the gate, without the driver having to open a window. If 85 percent of customers are signed up for this automated service, it means fewer labor costs and faster service. If a driver has opted for LPR, they could gain specific benefits. With LPR, there is no expense related to providing a windshield tag, as a driver would simply pull up into the camera’s range, and the system would then read the license plate.

The downside is the cost of the infrastructure required to set up cameras to read license plates, which would be more expensive than a typical RFID reader. There can be issues with custom license plates if they are muddy or otherwise difficult to read. Even the orange on Florida’s license plate can sometimes interfere with LPR systems. With RFID, one or two readers would typically be installed for each lane.

Gates are the simplest applications of RFID for vehicle recognition, such as the entrance to a gated community or a parking lot. The goal is to identify an authorized vehicle and trigger a response, which would be the automatic opening of the gate. This spares the driver from having to open a window, scan a card or interact with a guard. Typically, the tag-read event is not stored or managed in a system that tracks activities, but simply serves the function of opening the gate.

Ensuring the readers capture every RFID tag at a specific position, and not stray reads around it, requires some planning and testing. Most car washes have multiple lanes, which poses a challenge when it comes to reading stray tags, such as one applied to a vehicle in a different lane. The primary consideration for these companies is to make sure they optimize the fixed reader’s position and power to ensure, for instance, that the system does not capture the car behind a customer, immediately beneath the reader.

Car washes typically install two readers, with antennas located directly above the lane, aimed toward the position of a car’s windshield. Usually, the antennas are mounted on top, in order to read the tags on each vehicle’s front windshield. Getting this right is not always simple, however, and it requires testing and re-positioning or angling the antennas for all kinds of vehicles and potential locations in the lane, where vehicles may slow down and pass.

Applying Windshield Tags

Planning a new RFID system requires setting up a specific and clearly delineated interrogation zone in which each car should be positioned for reading. Moreover, testing helps to identify whether the reader is optimized to capture all the tags that might perform differently across different windshields and vehicles.

Whether for toll collection or at a car wash or gate, the tags interact with the readers in more or less the same way. Tags applied to cars are exposed to conditions very different from those inherent to many other RFID tagging applications. Extreme temperature ranges and high sunlight levels could impact the performance of standard tags, so dedicated vehicle-tracking tags are advisable.

Tags can be mounted on either the inside or outside of the windshield, and those mounted outside will experience the most challenging environments. Some tags can be printed as needed in order to customize the data linked to each specific tag ID. The design of modern-day cars provides a challenge for RFID tags. Many new or recently built vehicles contain metallic content in their windshields for shading purposes, which can detune RF transmissions.

Manufacturers have built in a solution, but many drivers are unaware of it. Cars come with a dedicated space for RFID tags to be applied, where mesh black dots are present.

“Most consumers just slap the tag on when they receive it in the mail,” Black says. They fail to put it in that dedicated area, he notes, “and then they find that their tag isn’t reading well.”

Tag Security to Prevent Fraudulent Use

It benefits the providers of these tags to make sure people understand where the tags need to be applied on a windshield. There are other vehicular tags available, however, such as rear-view mirror hangtags. These are best designed for temporary applications in which they could be removed from a car and then be reused. One challenge faced especially by car washes is preventing a tag’s misuse: namely, preventing a consumer from taking a tag from one vehicle and loaning it to a friend or family member to give them free washes.

Some tags offer security features to prevent this kind of fraud, Black says. For instance, Metalcraft has developed a tag known as the Dura Destruct, which detaches the chip from the antenna if it is removed from a windshield. This is a two-part tag, Black says, and the adhesive on it is strong. “But if you do manage to pull that tag off,” he notes, “it actually leaves a small portion of the chip behind on the windshield,” rendering the tag inoperable.

Other companies offer similar security features by which a tag would be destroyed, either by ripping the antenna off or damaging the chip. When it comes to tolling deployments, a tag typically must be put through a gamut of quality-control testing in order to ensure that it will perform well within all the potential tolerances that would prevent tags from failing in the field.

An E.U. Opportunity in the Upper ETSI Band

RFID tags that can be universally employed for automated vehicle tracking are available to customers in Europe when companies deploy specific RF bands. Currently, the European Union authorizes RFID transmissions in the lower ETSI bands, 865 to 868 MHz, whereas in the United States, the FCC band is identified as 902 to 928 MHz. That means some tags will not perform the same in both regions.

Europe also has access to the upper ETSI band (915 to 921 MHz), which would enable a tag to be globally useable. Companies in some parts of the European Union are starting to take advantage of this. “You have that global bandwidth,” Black says, by employing the upper ETSI band. The bandwidth also offers an increased output power, he notes, which typically is 2 watts in the lower ETSI band, but up to a 4-watt output allocation in the upper band.

“You are more than doubling your read range,” he notes, “and it also improves faster communication between tags and readers.”

This is especially important in applications such as vehicle tollways, Black says, adding, “You can imagine that with the tolling industry, that faster, more sensitive, easier data collection allows for much more accurate information.”

Overall, he reports, tag performance has greatly improved, with sensitivity typically double what it was a decade ago. In addition, costs are dropping with the diminishing size of chips. Manufacturers that previously might have produced 50,000 chips on a wafer can now produce up to 500,000 on a single wafer, thereby reducing waste and material use.

Key Takeaways:

  • The optimization of RFID readers requires testing and the adjusting of antenna installation, reader sensitivity and read-zone configuration.
  • Tag application instructions help vehicle operators understand where to apply their new RFID tag to ensure it operates properly on a windshield containing metallic materials.