Course Measurement: How It Works and Why It Matters

Great race directors are constantly looking for cost-effective ways to enhance the quality and reputation of their events. Nevertheless, many assume that USATF-Certification is not within their budget or that the process is complicated and intimidating.

The reality is that a professionally-measured, certified course is one of the smallest expenses in a road-race production budget, and it is not even an annual expense. Provided there are no changes to the course, due to construction, etc., a USATF-certified course is valid for 10 years and a World Athletics certified course is valid for 5 years. 

Why course measurement matters

The bottom line is this: course certification enhances the reputation of an event and helps attract more runners. And none of the “alternative/DIY” methods of measurement are even close to the accuracy of a certified course.

Runners expect an accurate course, and an increasing percentage of runners will only run certified courses. They want to be able to compare their time on your course with their results on other professionally-measured courses.

Even if one attempts to make the argument that runners don’t really care about their times (if that were true, why are so many using their own watches and phones for time? And/or why even hire a timing company?), we must consider that many participants’ sense of accomplishment is directly related to completing the actual advertised distance of the course.

Based on a study by Gary Brumley of TX Course Works, over 70% of runners polled indicated that a short course would negatively affect their sense of accomplishment. (Courses which have not been professionally measured are virtually always short.) 

A certified course lets runners know that you value them enough to provide an accurate course, and it can help your race stand out among the competition. If a participant asks whether the course is certified and the race director's response is, “No, but I ran it twice with my Garmin and mapped it out in PlotARoute,” that participant is not going to be convinced (with good reason). 

Saving on the nominal cost of course measurement is self-defeating. It’s like throwing a fundraising gala and then serving Pop Tarts. It’s no wonder why participants don't have a great experience or want to give more.

DIY vs professional course measurement

Some race organizers wonder why they can’t just map a course on MapMyRun or Strava or even run it using their own Garmin. Isn’t that good enough?

In my experience, at least 99% of uncertified road-race courses are very inaccurate - and almost always short. When I say short, I don’t mean by some trivial amount.

The average half marathon that a race director maps out and sends to me for measurement/certification is approximately half a mile short, when measured using USATF/World Athletics approved measurement procedures. This large discrepancy in distance would result in a difference of four to five minutes in finish time for the average half-marathon runner, and even 5K distances typically measure closer to 3 miles than a full 5 km.

Similar inaccuracies exist, to varying degrees, in all distances of uncertified and “Strava-certified” road race courses - whether measured using digital mapping, GPS, a measuring wheel, a car odometer, bicycle odometer, or some other uncalibrated device.

Despite the near-guaranteed failure of these methods, some race directors with uncertified courses are convinced that their course is the single exception and still somehow accurate. I’m sorry to burst this bubble, but if a course has not been measured using USATF/World Athletics approved procedures, there’s virtually no chance that it’s close to accurate, even if it was intentionally mapped long. 

Is your 5K really a 5K?

The question then becomes whether such significant inaccuracies are acceptable when a road race has advertised itself at a given distance (and has presumably hired a timing company to record runners’ times on that incorrectly advertised distance).

The course is the foundation for the entire event. If the goal is to provide an exceptional experience for runners, accurate distance is non-negotiable. If that is not possible, call it a fun run or don’t advertise the distance at all. Save the money on a timing company, too, as one’s time is meaningless without an accurate distance, and vice versa.

I believe that if more race directors and race committees understood how truly inaccurate the vast majority of uncertified courses are, the question of “when to certify and when not to certify” would not even be up for legitimate discussion. 

The great Ted Corbitt, who represented the US at the 1952 Olympic Marathon, was the founding President of New York Road Runners, and has been called “The Father of Long Distance Running”, could also be called the father of course measurement in the US. The incredible process that he developed, along with John Jewell in the UK, is still in use today.  

As Corbitt himself said, “The real prizes or rewards for most long distance runners are the times they record at various distances. To make recorded times meaningful, road racing courses should be accurately measured…Man insists on measuring time (easy to get accurately) and distance (difficult to get accurately) for comparison purposes. Athletes and fans assume that the correct distance of the race course is the advertised distance and they relate timed results not only with past performances on the course but to times made on other courses of the same distance… Road race sponsors can do a great service for the sport by accurately measuring the course.”

Personally, I couldn’t agree more.  

How an accurate course measurement works

Certified courses are measured using a device called a Jones Counter, which is attached to the hub of a bicycle wheel. For me, the counter typically measures about 17,350 counts per mile.

Jones Counter mounted on a bicycle wheel

Because temperature and tire pressure affect the number of counts in each mile or km, the Jones Counter must be calibrated at least four times before each measuring session and another four times after each measuring session. These calibration rides are performed on a straight, flat, paved calibration course, which is typically 300-400 meters in length.

Any calibration course is measured twice using steel tape, and both full measurements of the calibration course must be within about an inch. The temperature of the steel tape is also factored in. Once a calibration course is certified, it may be used for many future measurements. 

After calibrating, the measurer then rides the road race course twice, following the shortest possible route that will be available to runners. Unless there are course/lane restrictions (which then must be noted on the course map and delineated on race day), the measurer uses the full width of the road and measures 30 cm from the curb on turns.

This can often mean measuring against the flow of traffic and cutting across lanes of traffic. As a result, measurements are often done at night, in the early morning, and/or with the assistance of police escort vehicles.

Sometimes two or three measurers will ride together simultaneously so the course measurement can be completed in a single ride. And some courses are measured in segments, either all in a single day or over multiple days (with separate calibration data for each day).

Both complete measurements of any certified course must be within 0.08% (i.e., a maximum difference of four meters over the course of a 5K). The measurement which yields the longer course is used to determine certified distance. There is also a small “Short Course Prevention Factor” built into the measurement of USATF-Certified courses that ensures the course is at least the stated distance.

Further details on the measurement process may be found in USATF Road Running Technical Council's course measurement procedures manual.

Why alternative measuring methods are so inaccurate

Before we take a look at the process of course certification (which follows the course measurement), let's do a quick overview of alternative course measuring methods favored by some race directors and examine how they stack up to the process described above. 

Digital mapping

Regardless of which specific digital-mapping tool is used, most digital mapping is done using the default “follow roads” option or “follow popular routes” option. Zooming in on the digital course route will then quickly reveal wide turns and poor tangents. 

Even if digital mapping is done using freehand tangents, a course measurer will still almost always obtain a much tighter measurement (riding 30 cm from the curb on corners and hitting precise tangents throughout the course).

When I really need to get a decent pre-measurement distance estimate, I use Google Earth Pro (sometimes with historical imagery to remove foliage), and zoom way, way in, then draw hundreds of freehand tangents. It is possible to get a pretty close estimate of distance in this manner, but a “real-life” calibrated measurement is still tighter. 

In general, digitally mapping a course long is a good idea, but how long becomes a more nuanced discussion. How is one not just baking in a randomly inaccurate distance in the other direction at this point? It depends on many things, such as the amount of curves and turns in the course and the length of the course.

For example, if you were to add 0.1 miles for a 5K digital measurement on a winding course, you would need to double that for a 10K on a similar route. Many certified half marathons digitally map around 13.4 miles, although a half marathon on a winding course like NYC’s Central Park loop will measure longer with digital mapping than a certified half marathon course with many straightaways (like the Houston Half Marathon).

GPS

The limitations and inaccuracies of consumer-grade GPS devices available to us are fairly well-known.

On a straightaway, a GPS watch is often pretty accurate - turns and S-curves are where the real issues are introduced. A quick look at a runner’s Strava map for a race usually reveals where they ran wide on turns. There is even a noticeable difference in GPS measurement depending on whether the runner’s watch is on their inside wrist or their outside wrist on a turn.

And, even if GPS devices were totally accurate, the race distance still wouldn’t show up properly on watches because almost no one runs the shortest possible route.

Measuring wheels

This is potentially the “least-worst” measurement option of the bunch. Still, there are a number of problems:

1. A measuring wheel is only calibrated once in its lifespan. When we measure a certified course, we calibrate at least four times before and four times after every course measurement.
2. The wheel is subject to wobble and greater error just from fatigue as one pushes it throughout the course. 
3. Even if a measuring wheel were to be calibrated before and after each measurement (which never happens and would take forever if it did), it is often not really practical to measure the shortest possible route (twice) on a full race course while moving that slowly (i.e. using the full width of the road, often using long tangents that angle across and go counter-to-the-flow of traffic etc.).

Car/bicycle odometers

I think we can agree that there is usually no safe way to measure the shortest possible route using a vehicle (and of course a car’s odometer is not sufficiently accurate anyway).

Bicycle odometers are also notoriously imprecise. They would really need to be calibrated before every measurement because temperature, tire pressure, etc. greatly affect the accuracy of the measurements.

Ultimately, with any method, following the shortest possible route is a major concern.  

Course certification

After the course measurement has been completed, the measurer will organize the measurement data and paperwork before submitting everything for certification.

There are multiple layers of review before a course is approved, certified, and uploaded to the online database of certified courses. The measurer also creates and submits a detailed course map, which is designed to make everything as seamless as possible for the race director and course team on race day.

An accurate measurement is only half the battle. Course setup on race day is where most errors occur. To make sure the course is set up and run exactly as measured, many events also hire the measurer as a part of the race day course team.

Should you certify your race course?

Some have suggested that a course should only be certified if it's going to be a Boston Qualifier or used for national record attempts, but I find this suggestion deeply problematic.

What about runners just looking to compare their own personal performances or accurately assess their current fitness? There is no way for anyone to accomplish this without comparing apples-to-apples on professionally-measured courses.

This is not to say that you’ll never get a complaint about the length of a certified course. Almost every race director, even those with their “i”s dotted and “t”s crossed, can get complaints from GPS-loving runners that the RD’s course was inaccurate.

However, if the course is properly certified, the RD always has the best argument to fall back on and can simply direct runners to resources like the following USATF statement on the use of GPS.

Course certification vs USATF sanctioning

Before we wrap up, it’s worth mentioning the difference between course certification and USATF sanctioning, as this topic comes up frequently in my discussions with race directors.

Course certification deals specifically with the accuracy of the course. It really means that the course is accurately measured using the incredible process developed in the US by Ted Corbitt (in conjunction with John Jewell in the UK). 

Sanctioning, on the other hand, is more like a permit from the governing body (in the United States it’s USATF) that says a competition will take place according to the rules of the sport and the event will meet the safety guidelines of said governing body. Sanctioning can also have to do with event insurance through USATF.

Sanctioning is a different topic than course accuracy. However, it is worth looking into USATF-sanctioning from an insurance standpoint (whether supplemental or primary). Sanctioning is also a requirement for age-group national records (or open records) on a course and for any Olympic Trials qualifying times, etc. Given that we are seeing more and more age group records these days, even at local events, (thank you, carbon-plated shoes!), USATF-sanctioning is something that you may wish to consider.

Conclusion

Course certification is not something that an event “has” to do—there are many events that may be better off as “fun runs”!

The key for a fun run (i.e., a road race that is not professionally measured) is to be transparent about the fact that it is not an accurate distance. Then you don’t open the door for complaints about false advertising and risk making your event and your sponsors look bad. And a fun run doesn’t even need to be a standard distance— it could be a single, untimed loop around the park!  

When a road race advertises a distance, it is then a part of the sport of road racing. At that point there is an expectation of accurate distance, and the course should be professionally measured and certified (since none of the “alternative/DIY” methods of measurement are even close to accurate). 

Course certification is part of a great RD’s toolbox. When used alongside all of the other elements that lead to an incredible road race, it helps attract more runners and enhances the reputation of the event (making the RD and event sponsors look good). And the entire process is often much easier and more affordable than race directors expect.

Matt Slocum

Precision Course Design

Matt Slocum is the founder of Precision Course Design, a specialized company which provides consulting, course measurement, USATF-Certification, World Athletics Certification, Pre-Verified courses, and meticulous event-day course management services.