Starting back in June 2005, John Brammall who sadly departed a couple of years back, started a regular contribution to what was our monthly newsletter, O-Know.  John’s comments which he named Controllers Corner, are as relevant today as they were back then.  Valerie has kindly allowed us to reuse John’s Controllers Corner columns so they will become a regular contribution to our newsletter.  Valerie sees it as a fitting tribute that his contribution and passion for orienteering lives on and that through the column he continues to give back to the sport. Those he had encouraged or controlled still acknowledge and apply what they learned from him in course planning and fairness.

The following article was provided by John and appeared in the Jul 2005 edition of O-Know.

Dog-legs

The Competition Rules for Orienteering Australia include a really useful Appendix (2) on Principles of course planning ( - you can access this through the OT website.

Paragraph 3.5.4 Fairness of control sites states: ‘It is necessary to choose control sites with great care and notably to avoid the ‘acute angle’ effect where incoming competitors can be led into the control by outgoing runners.’ In other words – avoid dog-leg controls!

A key aspect in course planning is to ensure fairness. A dog-leg control is potentially unfair. We can’t predict where runners will be at any given time, so with a dog-leg, some runners could gain a benefit, while others will not.

Dog-legs

In the above examples, the legs A-B-C show a sequence of controls where runners leaving B are going to be running away from following runners (from A), and will not give away the control (B). Contrast this with the sequence D-E-F where if there is a runner leaving E to go to F, there is the strong probability that anyone approaching E from D will see them, and profit by it. This is a fairly obvious case that course planners can correct.

The legs G-H-I show a more complex situation. The leg from H to I offers interesting route choice either to the right along the spur and over the creek, or to the left (back towards G)to a creek crossing near the rock faces. This second option potentially creates a bad dog-leg. If the course planner wants to preserve the H-I leg, then the approach to H needs to be from a much more southerly direction.

It is very easy to get caught out by this third situation when we are course planning. Contours, vegetation and actual route choice can create an unexpected dog-leg. We really need to look carefully not only at how a control is likely to be approached, but also the direction in which runners are likely to leave the control, and what terrain features might affect this.

A couple of final points:

It is possible that what looks like an obvious dog-leg might in fact not be one because the terrain will force runners to approach and leave the control in such a way that avoids the dog-leg.

It is not as critical to avoid dog-legs in sprint events because of the complexity of a large number of controls in a compact area (with routes criss-crossing).

Dog-legs tend not to be of concern in MTBO – but still need to be looked at in terms of fairness.

Overall, avoiding dog-legs will help us to set fairer courses.