Why does it seem that the most error found on a closing boundary have most of it error half way or in the closing angle. I've heard that the further you go the more error can incorporate within your loop. But after you turn your closing angle it can drastically change especially if ran correctly. Lots of human error along with rough terrain and weather play a lot in a closed traverse but it is truley hard to get an infinity closed traverse, meaning 1 and ifinity on a closure. At least here in the south.
It's not that the error occurs at that location, it's that you don't have a true means of assessing the amount of error in your traverse until you both get to your closing point and then observe the closing angle. If your closing point is your also your POB and your closing angle is to the same line that you began your bearings from, then the errors you are finding are only those in the observations you made in your traverse.
If you are closing a known point other than your POB and closing your angles to a different known line than the one you started from, you are observing the result of both the errors within your measurements combined with the effect of the errors and adjustments of the previous work by others that was done to relate your beginning known point and baseline to your closing known point and baseline. The more separation between your starting and ending points, the more effect that the results of the previous work by others will factor into your misclosure. Either way, unless you are adding to the previous network with the intent of strengthening it with additional connections and observations, or unless you find an obvious blunder in the previous control, you generally will treat it with the fiction that it's without error and apply an adjustment to your own work on the assumption that the errors in it are not the result of mistakes, that any systematic errors have been accounted for, eliminated, or are otherwise negligible, and all that remains are the unavoidable random errors that are inherent to any measurement and are primarily functions of the limitations of precision of your equipment and methods and of the human abilities to precisely repeat fine measurements.
It's those random errors that make an infinity closure so difficult to attain. Using conventional equipment for a traverse (total station using IR or laser to measure distances), you can claim skill and good practices when consistently attaining 1:50,000 or so (a bit more or less, depending upon instrument precision, geometric shape of traverse, length of courses, etc.). If you get an infinity closure, it is strictly a matter of luck. It means you've hit the lottery of compensating errors.
It's kind of like if I were to go golfing a lot. With a good set of clubs and using quality golf balls and a lot of practice hitting the ball in the right direction, I might be able to get it on the green on the shorter holes with reasonable consistency. If so, I can claim a certain level of skill by getting on the green in one shot. But if it ever sinks in the hole on that first shot, that's pure luck.
I think that your right. I know that closing someone else traverse to yours as a tie is one thing but closure on your own so called traverse is another.
Every measurement has error. If it helps, picture every line vibrating kinda like a guitar string not fully attached at both ends... twang!
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Even when you get a wonderful closure it may be that you had compensating errors along the way and many of thhe points are futher off than your closure indicates. More checks are always good.
I have closed flat before.
That does not mean that it was all perfect.... It means that it accidentally meaned itself out!
I once ran a compass and tape traverse through the woods, to get the centerline of a creek. I had total station traverse to tie to, at both ends. It closed flat, (I knew the declination). But, any one of those creek coords could be off a half a foot or so.
If you want to close flat, you need to be less accurate. Layout a 100 x 200 rectangle with a 1' transit and by all means only turn your 90s once. I knew a survey professor whose favorite trick was cutting a foot out of a 100 foot steel tape and having his student run very precise traverses. The closures were great but the survey was not accurate.