How to switch from a 5 km to a 3 M

Tom, you have given us too little information for a definitive answer, I think.

Do they want to keep a common Start/Finish? If so, you could calibrate, then move Start/Finish closer to the loop. But, I think this would require a complete re-do, as the map would have to be changed, and it would not match the map for the old cert.

If they don't mind the Finish being .10686 mile from the Start, you could just finish at the 3 mile, if you calibrated, then measured to the 3-mile spot, from the Finish (unless the 3 mile location was already a certified split). This will verify the 3 mile is truly 3 miles from the Start, and allows them to cut the race short from the certified map. In my opinion, I would then do a second ride, from Start to 3-mile/Finish, and issue a new cert, if the measurements were within tolerance.

I think a new cert should be issued, since the map will have to change. You will have to do at least one complete ride, after making the adjustment, to verify tolerance.

My opinion.

All sorts of things one could do here, some of which depend on when the course was originally measured.

1. Truncate course at the 3 mile mark. If the course was measured earlier this year and the counts from the start to the 3 mile mark are within tolerance, you simply use those measurements and resumbit the application with a new map, and you have a new course with a 2022 expiration. If the course was measured before this year, the new course would expire ten years after the measurements were first submitted for certification.

2. Shorten the start/finish spur. This could be done with a steel tape. Move the start and finish approximately 86 meters toward the mile mark. Move the mile and 2 mile marks 86 meters toward the finish. Draw new map. Done. Again, if it's an adjustment of a course measured earlier this year, it expires in 2022. Otherwise, it expires ten years from when first submitted for certification.

3. A combination of the above- depending, of course, on the logistics of the start/finish.

I don't see any reason to perform another ride in any case, unless by doing so you would extend the course life for a full ten years. We've established that one can do that to an expired course. Can you extend the expiration of an active course with one ride?

Tom
I wouldn't have posted this on the Board - Bob Baumel will have a stroke.
I would be very curious as to "why".

No hospital stay for Bob because- I goofed.
It was actually a 3M to be changed to a 5 km!
The 3 Miler was an Out and Back with a common Start and Finish. What they were hoping for was the move the T-A 88 m farther out and then relocate the 2 and 3 M splits.
Would that work?

It's only a 5k. I would re-meassure the entire course again. By time you go out and start shifting things, you would be done. Plus Tom you need the additional experience

I'm actually heading out to remeasure a 3 mi/5km course that's used every year. This is a multi-loop course with a common finish and the starts 188m apart. I can tell you that the 3 mile race gets 4 to 5 times the entrants of the 5km - people must really hate walking that extra distance