RFID Eases Border-Crossing Traffic

By Samuel Greengard

The Mexican and U.S. governments worked together to automate toll collection.

Every day, thousands of vehicles stream across the international border between Ciudad Juárez, Mexico, and El Paso, Texas. Many Mexican citizens are daily commuters, driving to jobs and school, as well as to visit family members. In some cases, lines into the United States can snake for a mile or more, and it can take hours to travel across the Ysleta-Zaragoza International Bridge, which spans the Rio Grande.

An RFID-based automated toll-collection system, deployed roughly a decade ago to ease bridge traffic, would often break down or fail to function with some tags. "The previous system had become obsolete," says Pedro Dorantes, the Ysleta-Zaragoza International Bridge's director of operations.


Grupo Cadi designed and built the electronic toll-collection system.



Promofront—which operates the international bridge for the Mexican government and has collected tolls since 1991—and the Mexican government both recognized the need for a more efficient system several years ago. In May 2012, Promofront switched to an advanced RFID system. The Mexican and U.S. governments worked in collaboration with the company—as well as with its technology provider, Grupo Cadi—to develop and implement the custom-designed technology solution.

The Ysleta-Zaragoza International Bridge actually comprises two separate bridges: one with four lanes for commercial vehicles, and another with four lanes for passenger vehicles and two walkways for pedestrians. The RFID solution was deployed on the passenger bridge. Motorists who pass a security check, pay a fee and purchase an RFID tag for their vehicles can drive through the crossing with little or no wait.

In the United States, RFID is increasingly being employed to automate toll collection for roads, bridges and tunnels. In addition, U.S. Customs and Border Protection (CBP), a division of the U.S. Department of Homeland Security (DHS), has begun using the technology to gauge backups and help ease commercial congestion at five ports of entry in Texas (see RFID Readers Installed at U.S. Mexican Bridge Help Ease Traffic Congestion). CBP and some states have also turned to RFID-enabled travel documents—including passports and Enhanced Driver's Licenses—to streamline passport checks at borders.

Bridging Technologies and Borders


When Promofront turned to Grupo Cadi to design and build the new system, the starting point was a flexible platform that provided high performance and had the ability to expand during the months and years ahead. It was also essential for the current system to coexist with the new solution, since the older technology had thousands of users, and it would have been cumbersome to replace all of the tags at once. Promofront decided to replace the old tags as they expired (the tags remain valid for one year, so the old system would no longer be required after a one-year span).

The existing system utilized ultrahigh-frequency (UHF) RFID technology but did not adhere to Gen 2 standards. "We recommended a gradual migration to [UHF Gen 2] RFID technology that meets with the standards accepted by the Ministry of Communications and Transport," says Alejandra Ibarra, a business-development specialist at Grupo Cadi.


The Ysleta-Zaragoza International Bridge



The automated RFID system has been installed on a dedicated commuter lane (DCL) to the United States. A small metal box contains the reader and antennas: an Impinj Speedway Revolution R220 reader, designed to block out noise and interference; a general-purpose input/output box (GPIO) that manages the signals and power; a circular polarity RFID panel antenna from Laird Technologies that operates at 902 MHz to 928 MHz; and Laird die-cast enclosure RFID antennas that work at 860 MHz to 960 MHz.

In addition, Grupo Cadi developed an electronic device that allows the two RFID systems to coexist. "The function of the electronic circuit is to receive the opening signal sent to the gate from the GPIO box," Ibarra states. "It channels it to a relay that is responsible for closing the circuit, preventing the shock of electricity between the two systems that coexist at this time."

Motorists who want to use the RFID-enabled DCL must first register with the DHS for the Secure Electronic Network for Travelers Rapid Inspection (SENTRI) program. The program only accepts low-risk travelers, and applicants must undergo an extensive background check in order to qualify. Once registered, a user may purchase an annual tag from Promofront that contains a Smartrac DogBone RFID tag with an Impinj Monza chip encoded with a unique identification number. The tag, which is affixed to the upper right side of an automobile's windshield, is not reusable and has a lifespan of roughly five years, Ibarra reports.

Grupo Cadi developed software that connects the tag's ID number to the motorist's record stored in the software. When a car pulls up in the DCL, the reader transmits the ID to the software and brings the information up on a screen. A booth guard verifies that the information matches the membership associated with the car, but there is no need to manually enter document information. The guard indicates if everything is valid in the software application, and the server sends a signal to the GPIO to open the gate.

It took roughly a month for three programmers to develop the software and test it for flaws. Over a period of weeks, Grupo Cadi and Promofront installed the equipment and tested it on the DCL.

RFID in the Fast Lane


So far, Ibarra says, approximately 3,000 RFID tags have been issued to motorists, though Promofront expects to distribute a total of 17,000 tags within the next year. It takes two to three weeks for a person to be cleared for SENTRI registration.

To date, Ibarra adds, there has not been a single failure or breakdown, and the RFID system has correctly read every tag. "It has created a new level of efficiency that didn't previously exist," she says. Previously, motorists had to wait two to three hours to cross into the United States, but now, it takes just a few minutes. What's more, the system is providing cost savings for Promofront, since it reduces the amount of time and money previously spent processing paper tickets.

Motorists are required to deposit funds (currently about US$4,200 per year) to use the express lane. Promofront's management is looking into expanding the use of RFID to include prepaid tags that would work in a similar manner as prepaid phone cards, Ibarra says: A person would purchase a specific denomination, and the card would expire once the value was used up.

Promofront also plans to deploy the RFID system on a lane for trucks and commercial vehicles within the next year or so. Approximately 25,000 trucks travel between Ciudad Juárez and El Paso every month, according to Dorantes. "We are not making any changes to the current system," he says. "It is working exceptionally well. However, we do plan to expand the automation by applying the RFID solution to other lanes."

"The project is special," Ibarra states. "It has greatly simplified border crossings, by eliminating the need for cash. This represents the future of toll collection at international borders."