The turn around point is really a concern for race walkers. Most race walking courses are set up and measured with wide sweeping turn around comfortable for walkers not to break stride or form – judges are generally watching. Yet for running events, I think it customary to measure to a single point in the center of the road for a turn around. The turn around must be well documented as are the start and finish locations.
The out and back distance measured is equal to two measurements. You have measured the “distance” twice. The same can be said for a 5 km out and back course, measuring 2.5 km twice.
The suggestions given in our Manual under Course Measurement and Certification Procedures APPENDIX B - Course Layout says, “Small races and ultra-marathons are conveniently held on small loop courses, with each loop being from one to ten kilometers (one-half to six miles) in length. Certify the loop itself as a closed loop course. Once the closed loop is certified, all integral multiples of the loop are automatically certified. Thus, you may be able to certify a 100 km course with 10 km of measurement (twice over a 5 km loop).
If the closed loop course can be made an exact standard distance such as 5 km or 5 miles, races of several different lengths may be held on it. Intermediate splits which are integral numbers of loops are also certified and considered valid for record purposes. To set up a closed loop course which is an exact standard distance, refer to the discussion below on laying out a course with fixed start and finish points.”
Further, in the Manual it says, Course Measurement and Certification Procedures, The Shortest Possible Route, "When measuring a turn-around point, cycle up to the position of the turn, freeze the front wheel, record the count, reverse the bicycle, and proceed back in the other direction. Do not cycle "wide" around the turn."
