Monday, January 14, 2013

Measuring Marathon Courses by Bicycle

translated by Brett Larner

The full marathon is a sport where you compete over 42.195 km, but how do they go about measuring that distance?  Today we're going to look a little bit at how they go about certifying the distance of a marathon.

The reality is that major international marathons use a bicycle to measure the distance.  This rule is an international standard, and the same method of measurement is used everywhere.  It was put into place in 1986.  In order to ensure that the same method is used everywhere, a bicycle that meets IAAF specifications must be used for measurement.

In the case of Japan's major marathons, to be certain that the distance is correct a provisional measurement is first made.  Before the course is certified using a bicycle the course is measured using a 50 m-long length of wire to determine that it is in fact 42.195 km.  When a bicycle is used the estimate of the distance can vary slightly depending on the weight of the rider, so the Japanese method of using a wire is probably more accurate.

When it comes to course measurement the IAAF has a lot of other rules as well.  Believe it or not, one of them is that the course can be up to 0.1% too long and still be certified as an accurate distance!  That means that the IAAF has decided that a marathon course can be 42 m too long and still be considered OK.  Conversely, they specify that if a course is a little bit short it won't be certified.

To avoid that there are a lot of cases where they add a little extra to the distance.  Even at races where government bodies are acting as the organizers!  You can find reports that the distance of a race was incorrect, and if you research it a little further you will find that in a lot of instances the organizers didn't have enough time to measure the course on foot and that it was done by car instead!  As a consequence many races have fundamental errors in the distance of their courses.


Anonymous said...

The article leaves out a lot that goes into certifying a course and offers inaccurate info also. Using a 50 meter length of wire is NOT necessarily a more accurate way to measure a course - it's tedious, time consuming, bothersome (dealing w/traffic) and, as mentioned, not necessarily more accurate than using a bike. I know these things because I've measured courses for certification in the US (Michigan) since 1981.

To be certified, measurements include a .1% short course prevention factor (SCPF) to calculations. Note I say calculations and not to the course length. Our measurement technique isn't foolproof but has proven to be the most accurate around - thus we add the .1% to calculations to ensure the course is at least long enough.

Scott Hubbard

Anonymous said...

This article explains it very well with pictures etc