42,195 meters - not one less, and just a few meters more
THE WEDNESDAY COLUMN
2001-06-13The art of course measurement
When you run a particularly good time in a race, you often wonder right away if the course is short. If the course is advertised as "certified", you have some degree of assurance that it is accurate. After all that is what you have trained for: to cover the distance between the start and finish lines in the shortest possible time.
But what looks quite simple at first glance is a complicated endeavour.
Even an insignificantly short course can lead to a big scandal, and loss of reputation for the organiser. Many famous runners have been the victims when a course turned out to be short when re-measured after the race, and their records failed to be recognised.
So while time (and stop watch) cannot be fooled, there must be clear rules and procedures to make sure that a course is measured exactly. The body that did most to drive the introduction of uniform standards of measurement is the Association of International Marathon and Road Races (AIMS). After long years of dispute the AIMS standard has been recognised by the International Amateur Athletics Federation (IAAF) which means that it is now binding for all national athletics bodies.
The BERLIN MARATHON also did its part to drive the worldwide application of the new standard. On September 24 and 25, 1996, it hosted an international seminar on course measurement, chaired by John Disley from London.
Among the participants was Siegfried Menzel, a chartered surveyor working for the Berlin local government, and who achieved the highest IAAF/AIMS rank of "A" measurer. He is the man responsible for the exact measurement of the Berlin HALBMARATHON and 25k race distances as well as the world-record real,- BERLIN-MARATHON course.
To lay out and expertly measure a course of more than 26 miles in a multi-million metropolis such as Berlin is a very special challenge. First, the route is measured with the assistance of the metropolitan police, than it is validated by an international expert, usually John Disley or Hugh Jones (both from London). This is preferably done at night and with police assistance as well, as it happens in the middle of ongoing road traffic in both directions.
A similar procedure is followed for marking the shortest route a runner can take with the ubiquitous "blue line". Runners tend to cut corners where possible, which must be taken into account both when measuring and marking the course.
So, what looks simple, i.e. getting from A to B as fast as possible, and making sure that the distance covered is not one meter short, in a big city like Berlin turns out to be a surveying and planning masterpiece. Behind each certified course is a lot of work by dedicated people who want to give you confidence in the times you run. The official measurers job to lay out and certify a course that takes in all important sights, conforms to all rules, and allows a record pace to be run, truly deserves more than a gold medal.
But now to the column by Siegfried Menzel:
42,195 meters - not one less, and just a few meters more
First there is a brainchild, and the city map: The start and finish areas are chosen, important sights, monuments, squares, and roads are highlighted. A map measurer, or opisometer, is used to get a rough idea of the distances to be covered. Once the route is drawn out, one takes a car to see in practice if the course is suitable and safe for runners, power walkers, wheelchair athletes and in-line skaters alike.
The next important step, if all these requirements are met, is an accurate measurement. The officially accepted device to measure road courses is a mechanical counter (known as the Jones Counter) that mounts on the front wheel of a bicycle. The counter records 20 (in some cases, 24) counts for each revolution of the wheel. By riding the bike over an accurately laid out course to establish the number of counts per kilometer (or mile) one can then measure a course to a high degree of accuracy. Since all wheels differ in their circumference, the measure of one count needs to be established very accurately. To this end, one needs a stretch of road that is between 600 and 1000 meters long, the exact distance of which is determined with the help of an electronic distance meter (although steel tape is also entirely adequate for that purpose). This reference, or calibration, course should be rideable in both directions, and located in the vicinity of the start and finish of the race. The measurer, on the bike fitted with the Jones Counter, will ride the full length of the reference course four times, and each time record the initial and final readings of the Jones counter. This procedure is called calibration.
Calibration must be done before and after the actual course measurement, so as to take into account any changes of air temperature and air pressure happening during the (sometimes) hours of measuring, which all affect the wheels circumference and consequently, the value of one count. The average value of all calibration runs is then the working constant used for calculating the distances measured.
It is recommendable to fit the bike with a reliable electronic odometer and set it to the wheels circumference as established during pre-measurement calibration.
To measure courses on public roads, the measurer should be accompanied by one (or better, two) police cars. An own vehicle with an assistant to record the measurements, with whom he or she has radio communication, will enormously facilitate and accelerate the whole job. First, one must choose a clearly identifiable zero line (such as a lamppost marked with a number that cannot be mistaken) near the prospective start of the race.
This is the line where measurement will start. Here, the measurer, or the assistant, will record the Jones Counter reading and zero the bikes odometer. Now the measurer follows the shortest possible route a runner can be expected to take. After approximately 1,000 meters (on the odometer) he reads the Jones Counter at an unmistakeable point along the course. The assistant will record the reading and the exact location of this point (identify the street name, house number, refer to the previous or next street corner, lamppost, traffic lights, etc.). This procedure is repeated every 1,000 meters, at half-marathon as well as all 5-mile intervals, until the electronic odometer indicates 42,195 meters. After post-measurement calibration and determination of the working constant for the day, the measurer can proceed to exactly calculate the measured distances.
As a result, all points for which Jones Counter readings have been recorded, are attributed a value in meters with reference to the zero line. These should be only a few meters out of the full 1,000 meter or other splits mentioned above, the exact location of which can be re-measured with a steel tape and clearly marked on the course a few days before the race itself. Sketches are drawn of the start and finish areas, and a map with all relevant split marks along the course is prepared to make sure everyone can get a clear idea of the course layout.
Siegfried R. Menzel
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