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In the urban area in which I live, walk, run, bike, and do most of my measuring, the available paved paths are less than adequate to the heavy demand for off-road recreation space. XC and trail running, consequently, have grown rapidly here over a couple of decades. Many training runs and races in this region are conducted on unpaved single track. It seems to me that such a narrow path would eliminate the objection of "lack of repeatability" for measurement.  Stream crossings can be measured with a steel tape, and the distance added to the counter number. If we measure such courses in winter, when there is no overhead canopy, on a course with good sky view, GPS coordinates to identify timing points or turns would automatically work, even if the exact point as recreated would lie a few feet off the trail. The trail itself defines the measured path.

I scratch my head about the experiences of my brethren here who report difficulties with off-road measuring. It's more work than measuring on roads, certainly. My experience leads me to believe that experienced measurers who measure off-road courses with attention to detail in recording the path and in mapping can produce "certifiable" off-road courses that are reliably re-creatable and which are never short and not excessively long.

In addition, in contrast to Mike W.'s experience, I have measured off-road courses in which I identified many course points with engineer's flags. My second measurements have come out to well within .08% every single time. I then record these points with GPs coordinates. With one XC course I measured this way, I perennially perform the course layout. My wife Judy and I create a wide course with several hundred engineer's flags on both sides of the course. The SPR is defined by and confined by the flags. Course marshals ensure participants stay within the flags during the race. I will wager that this 5K is not even an inch short. Historic finish times by known athletes support this contention.

Further, given our apparent position of long courses being acceptable, it seems we could simply create some criteria with which to "pad" the measurement to prevent a short off-road course altogether - just as we in effect do for a measurement of a road course with two-way runner traffic. If we have doubts about the commitment of the race organization to perform proper course layout, we measure the full tangents on the road. Of "course", if the route is not laid out properly, this is not our official responsibility. But we ensure that the course will not be short, even if it may turn out to be longer than we may prefer.


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I have a 2000ish era GPS that might get down (eventually) to a 5' true value radius resolution.  And then, every time I move, I have to wait for the resolution to get back to something reasonable.  How many GPS points do you have for a 5K going through cow pastures in wide sweeping curves?  How repeatable is that GPS unit?  If it was me and I had to have 30 points and wait for them to get down to even that 5' best res, it would take 5 minutes per point.  Am I close? 


It was decided long ago that GPS coordinates cannot be the only definition of the location of the start, finish, or turn-around on a certification map. It was clarified at an annual meeting a few years ago that this also includes ANY point that defines the length of the course, such as the location of a turn point.

The fact that you can set up a large number of flags to define your route, and then use those to ride the course two times and get less than 0.08% difference is only one small part of repeatability. The real test is for another measurer to set up the course 3 months later based on your description, and then ride it and get with 0.08% of your measurement.

Exactly. This is why I use nearby fixed objects whenever possible, but of course, always for Start, Finish, and TAs.

With the GPS I use, I usually have to wait 30 to 60 seconds for the device to gather a good complement of satellite signals and produce a stable reading. And, then, naturally, the consequent reading will be accurate only to a radius of several feet or more. By going back to Google Earth at my desk, I am then often able to refine some field point locations thus captured, because I can determine the course path from the aerial imagery in combination with my field notes and my knowledge of the terrain. 

Oscar, you make a good point. This is why, when I am measuring off-road, I measure straight line points to straight lines. No "sweeping curves", for the reasons you mention.

I am not commenting to make a hard push against the ban on certifying off-road courses today. Yet, my experience informs me that, an experienced measurer using the right tools and careful practices can indeed create a course that is reproducible with sufficient accuracy. I am convinced that any good measurer could reproduce one of my off-road courses from my data and get within .08% of my measurement. Maybe I will figure out how to test this. One requirement would be that each inflection point would be fixed some small distance within the expected margin of error 90 degrees away from the recorded SPR. In my very humble opinion, this practice could add some distance over the nominal, and probably in the same range, on average, as in the case in which we measure a full tangent when the race nominally divides the road with traffic cones. 

As I mentally reconcile the fact that we certify that our courses won't prove to be short, but probably isn't as accurate as a steel-taped course; and that we are satisfied with certifying courses that may be long by many feet or yards, it seems to me that there should be no prima facie reason not to try to establish criteria for accurately measuring and documenting off-road courses. 

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