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There’s More To Measuring An Olympic Course Than Just Measuring It
David Katz is the official course measurer for the race walk at the Rio Olympics.

David Katz is the official course measurer for the race walk at the Rio Olympics.

Allison McCann

We’re on the ground in Rio covering the 2016 Summer Olympics. Check out all our coverage here.

RIO DE JANEIRO — It’s 7 a.m. The sun has barely risen, but for the better part of an hour, David Katz has been riding his bike around the course for the men’s 50-kilometer race walk later this morning. “More, more, more!” he shouts in the direction of a crew of guys arranging cones on the course, unhappy with the gaps around the second turn. Authority radiates from his neon orange vest, which reads: ROAD COURSE MEASURER.

This is not Katz’s first Olympic course measurement rodeo. Or his second or third. He was the official marathon and race walk course measurer for the 2012 London Olympics (there’s only one official measurer, tasked with ensuring that the length of a road course is measured to spec, but usually several others help) and is back again in that role in Rio. He’s been involved with Olympic course measuring as far back as the 1984 Games in Los Angeles. And he’s been organizing and measuring road course races in New York in his spare time for more than 40 years.

He’s a bit of a legend, as far as course measurement nerds go. “He is one of the best in the world,” said Wang Tak Fung of Hong Kong, a 20-year veteran of the course measurement game who came early to the race walk event to watch Katz in action. He seemed very impressed that Katz had lugged his steel measuring tape with him — a necessity only during official measurements (which were done weeks ago) and not for this morning’s slight tweaks and adjustments. The day of the race isn’t for official measuring; it’s for double-checking that the measurement is still accurate even after cones, barricades and water tables have been added to the course.

“Not too many people do a measurement like that, but I will do it right before the start of the race,” said Katz, a retired science teacher who lives on Long Island in New York. His attention to detail can be heard in every one of his shouts toward race organizers. He wasn’t pleased with the placement of the cones around the second turn of the race walk — they were creating too sharp an angle — so he rolled out his tape measurer (just a regular one) and adjusted them, ensuring that “no athlete has to compete for one extra centimeter.”


Photograph by Allison McCann

If, like me, you thought measuring a race course — marathon, race walk or otherwise — was as simple as driving a car around the circuit, you would be mocked by Katz and company. Turns out that a car’s odometer is fairly imprecise and that the preferred method of course measurement is much more artisanal. It requires only a calculator, 100-meter steel tape, a bicycle fitted with a GPS, and a device called a Jones Counter, which counts the rotations of the bike’s front axle — almost exactly 11,000 “counts” per kilometer.

To calibrate the bike for the official course measurement, Katz used the steel tape to measure out 300 meters on the course, taking into account any possible expansion or contraction of the tape from the day’s temperature (there’s an adjustment coefficient for that). Then Katz rode the bike back and forth from Point A to Point B to see how many counts of the Jones Counter occurred over that 300 meter mark. Voilà! The bike was ready to track the rest of the course.

“It’s very simple — I can teach you everything that I know about measuring if you have 15 minutes,” Katz told me. So then what makes him so good? “I’m a little bit more detail-oriented; I’m an official pain in the ass,” he said.

It’s not quite as simple as Katz lets on, but it is a simpler method than I expected from the person ultimately responsible for ensuring that any records set in road races at the Olympics are in fact records. “He’s exactly the person whom we need for a high stakes measurement like the Olympics,” said Imre Mátraházi, the technical manager of the competitions department of the International Association of Athletics Federations, the international governing body for track and field.

The trickiest part of course measurement, said Katz, is cutting the tangents. These can be corners or other parts of the course where athletes could find a shorter route. “If I was going to race you down the road for a million dollars and the road undulates, how are you going to run?” Katz asked. “You’re going to take the shortest path.”

During the official measurement process, Katz biked the course, usually less than a foot away from the curb or barricades, to make sure that an athlete couldn’t physically run anything less than the course he’s measuring. He did it several times, biking every possible route that someone could take on the course to ensure that none is too short. But there’s an extra precaution built in as well, known as the short course prevention factor: All international races must be an extra 0.1 percent long — meaning today’s 50 kilometer course is actually 50.05 km, or an extra 50 meters long.


Photograph by Allison McCann

Katz has had help at this Olympics, as is customary, from a Brazilian husband and wife, members of the organizing committee for the Rio Games. They did the initial measurements before Katz came through with the final verdict. “My measurement came out a little better than their measurement,” Katz said matter-of-factly, but he praised their work too. “They are top-notch measurers.”

With just over an hour left in the race walk, everything was going smoothly — no London race walk barricade disasters, at least. The current world record holder — France’s Yohann Diniz — was on pace to break that record (he would eventually fade well off pace). At the 25-km mark, he was almost 2 minutes ahead of Slovakia’s Matej Tóth, who eventually won. No world records were broken, so it’s unlikely that someone will re-measure Katz’s course after the Olympics are over. “I’m scared stiff about making a mistake; I double-check everything,” Katz said. But when I asked him whether he’s ever made one, he can’t remember a time he has.

Allison McCann is a former visual journalist for FiveThirtyEight.

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