Sneaker sensors keep marathon runners on track

Boston--Sensors attached to runners' sneakers, used in conjunction with RF technology, helped armchair enthusiasts and print media track runners of this year's Boston Marathon.

This system is the next step in the progression of technology used to track the marathon. In 1996, mats and sensors were only at the start and finish of the race. In 1997, the mats were at the beginning, halfway, and end of the race, but were only used to time and score the race.

The sensor system, used for the first time extensively for the Boston Marathon, was used in addition to existing tracking systems, and used radio frequency (RF) technology. Runners, with chips tied to their sneakers, ran over 25-ft-wide mats at 11 points throughout the marathon, the first being at the 5-km mark. The mats featured an antenna field on the outside that was generated by three smaller antennas on the inside parts of the mat.

As the chip on the runner's sneaker came into contact with the RF parabola, the parabola charged the chip, says Phil Graceffa, technology coordinator for the Boston Athletic Assoc.

The inner antennas on the mats read and picked up the unique code on each chip, which was collected on a laptop at each location. The laptops were tied into a Windows NT server, located remotely at the Boston Athletic Association's computer room at the Copley Plaza Hotel in Boston.

All the data was fed into a database, sorted and spit out, then copied onto the Boston Marathon web site, www.bostonmarathon.org, using a T1 link provided by Digital Equipment Corp. (Maynard, MA), Graceffa adds. Digital worked with Microsoft to develop the server based on Windows NT, and also provided all the interfacing equipment, desktop PCs, and notebook computers.

On race day, the web site recorded 1.9 million hits, double last year's total, according to Jack Fleming, spokesperson for the race. He attributes the higher traffic to a general increase in access to the Internet, plus more publicity for the site.

The sensor technology allowed all runners to be put on the web site. It also helped from a psychological point of view. In essence, the clock did not start until the runner crossed the start line. "It's very forgiving," Fleming says. "It gives runners in the back a sense of not being penalized."

The sensor system also helped make sure runners stayed the course. "If they don't show up at a couple of consecutive checkpoints, you'd have to look a little deeper to see if something happened with their particular chip, extenuating circumstances, or maybe they cheated," Fleming adds.

The sensor system's main use, Fleming says, is as the primary method for timing and scoring the race, a more passive scoring method than previous ones.

At the finish, runners used to hand numbered popsicle sticks or index cards to race officials. Next came tear-off tags with barcodes read by scanners. "Now, it's completely passive, where the runner just crosses the finish line and it's all electronic," Fleming adds.

The catalyst for the sensor technology project was Digital, working with the Boston Athletic Association, Fleming says. "They wanted us to do something that was cutting edge, and they provided us the resources to do this," he adds. "They spearheaded the cooperation and coordination to get this done."