Course measurement

With GBR over last weekend my next goal is a sprint tri on Sunday. But in the meantime we are busy in the office working on our next event, the Harry Hawkes Raceday. We have a new race this year , the Ditton Dash 10k, which starts at 8.00 on June 24, preceeding the Harry Hawks 10 (miles) at 09.30. Getting the distance right is obviously an important part of the race organisation and today we went out to do the final marking.

So how do you go about getting an officially measured and marked out course? There maybe short cuts but this is the way we approach it. First there is a discussion about a potential route, which is then followed up by initial on line mapping and on the ground research. Consideration is taken on road safety, the need for road closures, the suitability of the route for the proposed number of runners, and where permissions are required. This can take a lot of time. You need to speak to councils and a range of emergency services including. Sometimes these days all come together under the term SAG or Safety Advisory Group. But this is really down to local council administration.

Once you haves established in principle that the route is OK you then need to move to the official measurement which is required for the UKA licence.  At this point we have recced the course several times, perhaps introducing improvements on the way. For the Ditton Dash we had established a 10k route we felt would work well and knew pretty much where it would start and finish on Giggs Hill Green. We then booked Hugh Jones of the Association of Course measurers to come and measure the course.

Hugh measures using a standard bicycle with a special “Jones meter” mounted on the front wheel. Each revolution of the wheel turns a counter and multiplying the units on the calculator by a known distance figure converts this to metres. Hugh explains that there are a number of variables that he also takes into account. The bike tyre pressures, temperature and weather can all have an effect. To ensure accuracy on the day of measurement he checks the calibrations twice by cycling on a previously measured 300 metre strip which has itself been checked for distance using a steel tape measure.

It’s not unusual to hear runners claiming that a course is either long or short, as measured by there Garmin or Strava devices. While it is true that not all courses have been measured accurately, it is more likely that there is a small discrepancy in the device accuracy. Or it can be down to the fact that in races you often are not running on the shortest racing line.

When the course measurement is complete a certificate is issued. But the process is not yet complete. Sometimes adjustments need to be made to the actual start and finish positions and these need to be reflected in the position of the distance makers. With the Ditton Dash my original course measurements were short due to a changes we made to improve the route. This meant we had to move the start/finish line back by 80metres from the point we had measured. Thus when we came to mark the course Km points Hughs instructions read, for example: 3km: Embercourt Road, 101.4m before Lamp Post no 10 on right.

So on Wednesday this week Jennie and I set out on bikes to cycle the course and mark up the exact points for the Km signs. Jennie set Strava running on her phone and I set my Garmin watch, but these were just to provide us with a rough guide and check. The actual marks were measured back using a Surveyors wheel from the points on Hughs report. Everything was spot on from start to finish. And the Strava and Garmin were also both fairly accurate although neither matched exactly. In the end my watch gave the total measurement as 48m long (an error of just under 0.005%)

It was a great day for course marking with plenty of sunshine and pleasantly warm, and Ditton Woods were quiet and magical. Overall I think we have a great route. And should you decide to run the Ditton Dash on June 24 you can do so safe in the knowledge that it is an exact 10k and the Km markers will all be dead on the distance!