Sixteen-thousand people are running the Philadelphia Marathon Sunday — and every last person will get a time.

Over the summer, the New Yorker published an article about one runner who was cheating marathon timing systems. Here's a look at how race timing works, and what's being done to fight course cutting.

How it works

David Simms has been timing the Philadelphia Marathon for more than 20 years. He runs a company based in Michigan called Simmco Data Systems.

It was one of the first to use RFID timing to track marathons.

RFID is kind of like E-ZPass for runners.

"When you go through the magnetic field, which energizes up the RFID tag, it looks at the time on the controller box on the mat you're crossing," explained Simms. "And it time-stamps you with that exact time to the thousandth of a second."

At Sunday's marathon, six of these timing mats will be scattered across the 26-mile course, but the locations of just three are made public. There's one at around six miles, another at the halfway point, and one more at just before 19 miles.

"Then we have others that are different places just to make sure that you ran the whole course," Simms said.

Timing drama

Simms says cheating in marathons is very uncommon. But for two years, controversy in the running world has slowly built to a boil over one Kip Litton.

"The more conversation I had with him, the more I realized the guy was just a liar," said Wayne Kursh. "I disqualified him."

Kursh is the race director of the Delaware Marathon and the president of Races2Run.com.

Back in 2010, Kursh was contacted about the 48-year-old Litton, who had finished first in his age group in Delaware. The Michigan dentist was trying to run a marathon in every state to raise money for charity.

But soon it became clear that something was amiss.

Kursh then became one of many race directors who propelled Litton's mysterious tale into the popular press.

"None of us could catch him in the act," Kursh said. "We all had to rely on the technology of 'no splits, no pictures' to make our decisions to disqualify the guy."

Now what?

Kursh admits, Litton is far from the norm.

But the extraordinary — and still partially unresolved — case of how Litton cheated his way onto the award stand has still made some race directors bulk up on timing systems.

"We're putting more and more technology to use and putting more timing mats out on the course," said Kursh of the Delaware race.

"Most people don't cheat," said race timer Simms. "It really isn't an issue."

He says Litton's short-lived success in beating the clock is just an overhyped fluke.

"People are aware of him," Simms said. "All the timers in Michigan, the larger ones, they are aware of him. But now that they're aware of him, they look out for him."

Simms says most timing software red-flags potential cheaters automatically. In all, he says maybe a half-a-percent of finishers skip ahead to the finish line.

When they do, Simms doesn't really like to think of most of them as "cheaters."

"You get some older people, or people who just get tired, which don't affect the awards at all," said Simms. "Who's going to cheat to run a five-, six-hour marathon? They just got tired and they cut the course and went through the finish line."

For us non-runners, under three hours is the mark of an elite marathoner. Litton was shaving off enough time to put himself in that group.

Bottom line, Simms says, if Litton showed up on Sunday it'd be nearly impossible for him to cheat undetected.

"We'll catch him if he does," Simms said. "Whether it be him or whether it be the man on the moon."

Oh, by the way, no one named Litton shows up on Philadelphia's online registration list.