Heavy traffic is expected on roadways and the Internet for Sunday's Honolulu Marathon, which could have its largest field since 2002.

"Put it this way, if there's a lot of runners, there's a lot of Web traffic," said Mitchell Kahle, who helps manage the Honolulu Marathon Web site, which gets anywhere from a half-million to a million visitors annually.

More than 26,000 participants have signed up for Sunday's 26.2-mile race, and organizers are expecting about 28,000 by the start, which would make it the largest Honolulu Marathon since 2002.

The online runner tracking system is the most popular race-day feature, and allows Internet users to check on the progress of any runner as they pass four different checkpoints: 10 kilometers, on Monsarrat Avenue, near the Kapi'olani Park bandstand; half-marathon, near Calvary by the Sea in the 'Aina Haina area; 30 kilometers, across Kilohana United Methodist Church in the Hawai'i Kai area; and the finish.

Internet users can get results by typing in any runner, his or her bib number, country, city or state.

Runners are given a ChampionChip, a small plastic disk containing a mini transponder that is attached to their shoelaces. Special timing mats on the course record runners' times. Results are relayed via cellphone to a database that can be accessed through the Internet.

The Honolulu Marathon implemented the online runner tracking system in 2000. LavaNet is the Internet Service Provider of the Honolulu Marathon Web site, Kahle said.

The system will need to handle anywhere between 300,000 to 1 million visitors on race day, Kahle said. It can also handle as many as 10,000 simultaneous search requests, he said.

The tracking system is perfect for friends and family who want to check on the well-being of their runner, Kahle said.

"I think the biggest thing is people just want to know that their runner is OK, and making progress," said Kahle, who runs Sports Media Productions, which offers runners a personalized DVD of the Honolulu Marathon.

Once a runner crosses a checkpoint, Internet users can get results within less than a minute "if all things are firing on the right cylinders," Kahle said.

Despite heavy Internet traffic, the server that serves the Honolulu Marathon Web page has never gone down, Kahle said. But it did crash the City and County of Honolulu Web site several years ago when Internet users followed a link to the city site that offered traffic camera views of the marathon.

Kahle believes Global Positioning System technology and satellites will be used to track runners' exact position in the future.

"You will be able to follow your runner at every step of the course," Kahle said. "GPS technology will allow that to happen. Right now, I think it's a matter of not being economically feasible."

In the meantime, Internet users can follow their favorite runners through the Honolulu Marathon Web site.

"The technology in these races really goes hand in glove," Kahle said. "I think the races benefit by this greatly, and by extension, the participants benefit. It's a good system."

Reach Brandon Masuoka at bmasuoka@honoluluadvertiser.com.