Have you ever wondered how they measure the distances we run at road races? Course records, qualifying times, and world records all depend on an accurate measurement. A 10k race in London has to be the same 10k distance as a race in Tokyo. It’s not something that can be loosely estimated. Corners literally can’t be cut. And google maps can’t be used as the only way to plot out where your 10k will come from!
When running a race that weaves through the streets of a major city, how do they ensure that all athletes are running the same distance? In this post, we’ll take a look at the methods and science behind measuring road races. All of the below information can be found in the World Athletics official rules, but we’ve summarized it here in a way that explains the rules as well as the methods for measuring road races.
Supported Distances and Rules
Official races can only be the following distances: 5km, 10km, 15km, 20km, Half-Marathon, 25km, 30km, Marathon (42.195km), 100km, Road Relay
Any other distance is considered ‘unsupported’. While events may offer different distances, such as the 8km Shamrock Shuffle in , to be considered an official event within the World Athletics umbrella of governance, the event has to be one of these specified distances.
When it comes to road races, another important rule is that they take place on actual roads. World Athletics defines this as “made-up roads”. This is because the distances need to be measured on municipally supported surfaces, for which the actual distances are already known. There are provisions in the rules that the start and finish areas can be located within stadiums or other athletic facilities. There are also provisions for the realities of traffic and other factors that could cause small portions of the routes to be done on sidewalks or other paved surfaces if necessary, but these instances should be kept to a minimum. And yes, road races need to be on a paved surface. A race can get away with a very minimal stretch of the course being on a grass or sandy surface, but the rules clearly state that these need to be minimal as well.
Method of Measurement
The official distance of a race is measured according to the shortest possible route a runner could take while following the planned route. This means that you don’t have to worry about taking corners too tightly or too long! The race officials and organizers will have taken any of that into account when measuring their course.
Organizers will use what is called the “Calibrated Bicycle Method” to measure the official distance of the race. This method involves mounting a tool called a Jones Counter to the front wheel of a bicycle. This tool will measure the revolutions of the wheel and will use that as the basis to calculate the distance of the course. The organizers will plot out a general route using street maps and other commonly available tools. Then, they will measure the distance using the Calibrated Bicycle Method to ensure they have exact placements for the start and finish line that will result in the desired official distance of the event.
This process is both an art and a science, and for races to be deemed ‘official’, they will need someone from the governing body to conduct the measurement and certify the course length. To many races, that might not be important. A charity-sponsored 5k that exists only to support the goals of the organization will not be concerned about official status. But any race that will host competitors looking to get a Personal Best or use the race result to qualify for something else, will need to ensure they have official support and certification.
Races have to apply for course certification. As long as their route doesn’t change, they can use the certification for future runs of the race for up to five years. After five years, they’ll need to apply for certification again.
What About Turning Corners or Short Cuts?
The full distance of the racecourse is always measured in a straight line from start to finish. This line is often marked directly on the street. If you’ve ever run a major marathon, you will have noticed a bright blue line spray-painted on the street every ten or fifteen meters. The line is also emphasized on any part of the course which involves a turn. Any time a course turns, there is potential for a runner to take the turn too tightly or too widely, which could result in an impact on the overall distance. Running directly on the thin blue line is the way to ensure that you are following the exact path of the course.
Of course, not all runners are going to run in one long single-file formation throughout the race. If the entire street has been blocked off for the race, variances in distance are inevitable, especially if there are corners involved. For this reason, the rules recommend implementing a “short course prevention factor”. This means that a small amount of slack is built into all courses. The rules recommend this to be 0.1%, which merely means that a 5k race probably has an official distance of 5005 meters. See? You don’t have to worry!
In addition to accounting for the few meters that might be shortened due to corners, the short course prevention factor also helps ensure race organizers that the results of their race won’t be challenged or invalidated. It is always better to be a few inches longer than to be short in any way.
There’s Really an Estimate Happening?
Yes, it is true. If you want to run an exact 5km race, the best place to do that is on a track. Any race over the 15km distance will have some slack built into it. There will also be some level of estimation going on. It would be rare to find any slack or estimation that would have a material impact on the results of most runners, but it does happen.
We hope this explanation has helped you understand the process that race organizers go through to get their courses planned, drawn, and certified. As you can see, the distance of a race is never something taken lightly and the rules surrounding the certification of courses are robust. If you’d like any further information, take a look at the Book of Rules for World Athletics