UHF Solution Tracks 42,000 Runners at the New York City Marathon

ChronoTrack Systems, which developed the system with Impinj, says its single-use tags make life easier for race organizers and runners.
Published: November 10, 2009

My cousin, Diane Bownes, ran this year’s New York City Marathon on Nov. 1. I, meanwhile, sat at home and tracked her progress. Diane finished the first 5 kilometers (3.1 miles) in 27 minutes and 12 seconds; reached the halfway point in one hour, 44 minutes and 48 seconds; and completed the race in three hours, 40 minutes and 16 seconds. I was able to track her progress because she was wearing an RFID tag on her sneaker, and interrogators were set up at milestones along the 26-mile route.

RFID technology has been used to track runners for almost a decade. I believe the Boston Marathon was the first in the United States to use a high-frequency (HF) tag in hardened plastic, which was laced to each runner’s sneaker. Each time a runner stepped on or over a reader antenna laid across the road, the tag was read and the runner’s status was updated.

Photo courtesy brightroom.com

This year, for the first time, the New York City Marathon used an ultrahigh-frequency (UHF) tag from a company known as ChronoTrack Systems. The advantage of ChronoTrack’s system, according to Daniel R. Howell, the company’s president, is that the UHF tag is single-use—that is, it can be thrown away after a race—and it simplifies the process of matching IDs in the tags to numbers on the bibs worn by runners.

With most race-timing systems, a number is hard-coded into an HF tag, after which the HF tag is encapsulated in plastic to protect it. Runners typically have to put down a $30 deposit for the tag, which they can get back upon returning it. The race organizer has to take a so-called “chip file” (containing all of the serial numbers), associate each serial number on each bib with a chip number, and record that information. Mistakes are sometimes made, which means the runner’s time is not always accurately recorded.

Howell says ChronoTrack’s system eliminates this process. The company, which worked closely with Impinj to develop the system, provides labels embedded with a UHF transponder to the company providing the race-timing system. The bib numbers are written to the tag and printed on the label by a Zebra Technologies RFID label printer. The label is put on the bib and delivered to the race organizer, who hands them out to the runners.

The label is waterproof, and while UHF tags are difficult to read through the body, ChronoTrack solved that problem by creating a “D tag.” The transponder is arced away from the foot so that it can be read consistently. According to Howell, the read rate was 99.9 percent during the New York City Marathon.

Impinj developed special reader antennas that can be laid out across the road and protected with a special housing. “We’ve done a lot of races in the past year,” Howell reports, “but the New York Marathon is the big daddy. We had check lines every five kilometers and every mile after the halfway point of the race. There were a total of 70 controllers in 30 different control lines.”

The system was tied into the leader board and systems used by the TV networks covering the race. The New York City Marathon also developed some custom software that estimated each runner’s pace, enabling fans like me to visit a Web site and track the runners on a Google map over the entire course. Runners could also send updates via text messages when they passed a milestone, to up to four different text numbers.

It was a complex system that brought together several companies, Howell indicates. Impinj manufactured the chip and designed the tag antenna. MPI converted the tags into label stock. And Zebra supplied the printers.

“Our control points had an Impinj reader in it, plus Wi-Fi, Ethernet to connect to the Internet and GPRS to connect to the cell network,” Howell notes. “All the data was sent to our servers, and then to the New York Marathon organizers, which interfaced with the leader board and the TV systems. With that much stuff going on at the same time, there is a fear factor, but we tested it and tested it and tested it—and we nailed it.”

My cousin Diane was happy with her time, too. Me? I was happy to watch her progress on my computer.

Mark Roberti is the founder and editor of RFID Journal. If you would like to comment on this article, click on the link below. To read more of Mark’s opinions, visit the RFID Journal Blog or click here.