Accuracy of height / length / distance measurement
Comments about this discussion:
Started
Apart from the issue of resolution (see Discussion 84), there is also the issue of accuracy. In the Track and Road sections of the rulebook, there are rules about the quality and certification of time and distance measurement equipment and procedures. I believe this is a good thing, because it means that results (and records, for that matter) can be trusted. In the Jumps chapter, such requirements are absent.
I would like to formulate some requirements.
Comments?
Comment
(Just realized today that I'm on this committee) I wish I had something concrete to offer. From what I've observed at these competitions, High Jump bars are usually measured to at least two points along the bar, to account for any sag or out-of-level. This should be addressed. While the bar-holding posts can be marked with measurements, these will usually not be accurate due to irregularities of the riding surface, the way the bar is hung, etc. So while these markings can be used as a reference, actual measurent of the bar's height should be hand-measured for each setting, to know the actual height from ground to top of bar.
For Long Jump, this is easier because if a measuring tape is attached to the ground, one needs only to make sure the starting end stays accurate to the jump line, and that the landing measurements are accurately taken. Hand measurement is recommended when the competition narrows to 2 or 3 riders, or at least for the final distance riders attempt. Two measuring tapes will be better, to keep the bar parallel to the start line.
For Long Jump and high Jump on Platforms, a similar setup of measuring tapes on the ground can be used (two), with hand measurements taken as the competition narrows to 2 or 3 riders.
Comment
From what I've observed, in High Jump over bar, the poles on which the bar rests are marked in height (probably with a measuring tape attached to them, not sure). Setting both ends of the bar at a certain height is thus a height measurement. What matters more is the height at the lowest point of the bar (because it sags). This is always measured separately, with a measuring tape. This is a bit of a tricky measurement: the tape needs to be vertical (both laterally and transversally) or you would measure a too high height value. The other thing is parallax, if the tape is not against the bar and the observer's eye is not at the same height.
Secondly, would we have to phrase requirements about the accuracy (class) of the tapes/markers on the poles, and perhaps more importantly, the accuracy (class) of the measuring tape to measure the bar height directly?
High Jump results are expressed in whole centimeters, but the underlying accuracy should be significantly better - I feel 1 to 2 mm is appropriate.
Comment
Part 13B.7 Height and Distance Settings in the Rulebook says "In any case, heights or distances must be set as
accurately as reasonably possible." however I agree that the measurement guidelines could be better defined.
I can confirm that at least at the past 3 Unicons, Long Jump competitions had tapes on the ground on both sides of the bars / pallets or the pallets were measured on both sides. Same in High Jump competitions, the bar / platform was measured at 2 if not 3 points - which shows that by defining these in the Rulebook won't harm the event flow, as these are already done appropriately, just without being clearly stated in the Rulebook.
Comment
Mark is right; probably the most important measurement in High Jump is at the center of the bar; the point of the lowest sag. This is the height that the tire is clearing, not the height at the supports. The finished rule should probably specify that the lowest point of the bar is the "true" measurement of height at any given time, and that multiple measurements near the middle of the bar may be needed to make sure the lowest point is being measured.
Comment
OK, that covers the location(s) along the bar at which the height is measured. We could add the requirement to measure at least at the bar midpoint/lowest point in the rulebook.
What about adding a requirement about an accuracy class for the measuring tape/stick used. Would it be useful, or would it be overkill in view of the inherent inaccuracy of measuring the height of a round bar above a (probably) slightly uneven surface?
Comment
EDIT: my comment above is only about height of High Jump over bar. There's also height and distance measurement involved in the other threes Jump disciplines.