I had the honor of retracing a survey, that had some 30 courses, which were all rounded to the nearest tenth, and minute of bearing. It was some 15 acres, but failed to close by 0.64'.
I kinda sorta "Adjusted 'em back in".
I have heard the literal approach, of "Throwing it into the last course" (Well, it SAID to the POB!) is the logic for that.
And, I have gotten in the habit of sort of "adjusting it back in" because rounding is generally throwing less than 0.05' of error into each distance, and 0å¡0', and 29.5" into each course.
Then, after tying into enough of the POINTS on that survey, I get it "Close 'nuff" and go home.
But, it seems to me as semi problematic, when you know that it is random, and occurs at some places, and not at others. And, if there is NOT MUCH to tie into, as in only a few monuments left, then you just "Do the best you can" with it.
Now, what is happening, is land that WAS worth 2000 per acre, is now becoming worth 10,000 per acre. And, you don't really want trouble... you want the mechanics of your survey to be as sound as possible.
And, so I publish my plats to the hundredth, and second of bearing... but it's STILL a given that the survey is NOT that accurate.
Anyway, what do you do with this somewhat innocuous item, and what do you think is the MOST professional way to handle it?
Thank you,
It's just up for discussion.
BTW, I did have a girl at the tax office, inquire about it... "Is that as accurate as surveyors can compute it"?
I said, no, but when you know that the accuracy of your work is about that, then you in a sense are leaving it for a re tracer to "Find out" where the little slop shots are... I showed her one of mine, and what I do, and why...
Two philosophies, of looking at the SAME problem....
N
de minimis non curat lex
Loyal
My most recent adventure involving the same type of rounding was for DOT tracts acquired in fee for highway right-of-way purposes. Fortunately, our DOT will share their coordinate files if they ever existed. I received several pages of old computer printouts of the original data including the penciled in alterations that produced the final document wording. Seeing N 47D13'32" E and 1217.84 feet become N 47D14' E and 1217.8 feet shows the thinking of the officials higher than the surveyor at the time. These happened to be from about 1980. Finding the original data is especially helpful for rotating to the true bearing of a controlling line used as the basis of bearings
when I was a young buck (late 70s) I began working for an old salt. I would go out on a rural survey, find and reset, run my calcs (HP29c), then prepare a plat for his approval and signature. I discovered that he rounded my distances to the tenth, and directions to 20 minutes. He was firm that he would not consider publishing data he could not measure... He was correct, we did not have the ability to measure better than that reliably.
It was perplexing. It was in that same era and location that I heard of forcing the "error" into the closing course (The Horror of It All).
a couple decades later I had a computer and Star*Net... I tried inputting the rounded deed/map data in and run a closure. That worked great... but it made me search for more field evidence to raise my comfort level.
today I tend to ignore most measurement anomalies
The bearings and distances in deeds are there to help you find the corners and other evidence. After all evidence based options are exhausted you can use the record numbers to fill in the blanks. Your treatment of those numbers should be based on the likely sources of error at the time the parcel was created. If you are fortunate you will find enough to test the method used to restore missing corners.
You are a more precise measurer of angles and distances and should understand that you do not have to match his numbers to follow in his footsteps.
Paul in PA
Paul in PA, post: 421712, member: 236 wrote: You are a more precise measurer of angles and distances and should understand that you do not have to match his numbers to follow in his footsteps.
Paul in PA
I have mentioned before that surveying courses at Columbus State Community College emphasized limitations of surveying equipment and using documents to find controlling monuments. The following is an example of how a surveying history course (currently SURV 1420 Historical Surveying) presented that to surveying/engineering students.
[MEDIA=youtube]Xzk_0HX0lH4[/MEDIA]
It just introduces a form of uncertianty, which i find cumbersome, and sometimes not of high value.
Nate The Surveyor, post: 421797, member: 291 wrote: It just introduces a form of uncertianty, which i find cumbersome, and sometimes not of high value.
Excuse Nate, just what is your comment above referring to?
I am confident that the prior surveyor was quite certain in how he described the survey, within his level of precision.
Paul in PA
30 courses and miss closes by 0.64', that sounds pretty good to me. I would probably distribute the error equally between courses, unless there are certain courses that can be constrained by found monuments, adjoining surveys, or locatable features.
Force it together somehow. Unless you are using the helicopter method of boundary resolution, the final resolution is not going to look exactly like the deed anyway because it'l be controlled by local monuments. Of the 30 courses I assume you have at least a few monuments so if you hold the points it's not gonna look like perfect record no matter what you do.
When all fails, use least squares!
I think the Manual would advocate using a Grant Boundary Adjustment (scale and rotate) for courses between found mons. I like this because it's got a name (so you can easily define it in your notes), and the next guy can easily understand what you did and even replicate it with minimal computing power. I like Least Squares as much as the next survey geek, but I think there are better tools for this job for reasons other than the math.
I think a compass adjustment between found established monuments makes the most sense.
The Grant Boundary method assumes the angular relationship between successive courses is without error which seems unreasonable given that most Rancho boundaries were run at a very fast pace with a compass.
Dave Karoly, post: 421886, member: 94 wrote: I think a compass adjustment between found established monuments makes the most sense.
The Grant Boundary method assumes the angular relationship between successive courses is without error which seems unreasonable given that most Rancho boundaries were run at a very fast pace with a compass.
Bingo. Your method MUST have a foundation. At the very least make an educated guess based on the technology available and in use at the time of parcel creation.
Unless you have an indication that the last course wasn't actually run, throwing the entire misclosure into the last leg is a bogus rule that should never be used. Unless there is something to indicate otherwise, all courses should be considered to have been measured with the same equipment and methods, with no course being superior to any other course.
First off, recognize the significant figures of the numerical terms in the description. If they were described to the nearest .01' and 01", you wouldn't be nearly so concerned over a misclosure of six and a half hundredths in a 30 course description would you?
As others have said, equally balance both the angular and distance errors between verifiable physical evidence of the boundary (as Dave said, compass rule best for this). When resolving discrepancies of this sort, we are supposed to do so in a way that makes as little change to any of the courses as possible while giving effect to all of the terms.
If after balancing the courses between the physical evidence you've been able to find, the courses all end up being +/- 0.1 ft and +/- 1 min, then the person who made the measurements for the description did a pretty darn good job of it.
