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Uncertainty Due to Condition of Existing Monuments
Posted by Scott Bordenet on May 3, 2022 at 12:44 pmIn Indiana, we have a requirement for the measurement accuracy in boundary surveys (Relative Positional Accuracy, RPA). !!! This post has nothing to do with measurements. !!!
In Indiana, a boundary survey must also address the UNCERTAINTY in the availabilty and CONDITION of reference monuments (865 IAC 1-12-12-a-1). In the situation of a found, bent rebar, I could estimate a possible error of 0.15′ due to its disturbed condition. This is entirely my opinion based on what I saw. I have not done any kind of scientific or measurement analysis (though I could).
I am interested in what others believe is knowable, unknowable and how that is addressed in writing. Also, how others will address uncertainty and accuracy. What methods should be used to assess these things?
Give me your thoughts on how you would address the uncertainty of Harrison monuments and other types of monuments (large, medium, small stones) that you find.
dmyhill replied 1 year, 11 months ago 15 Members · 35 Replies- 35 Replies
Quickly reviewing the cite for the first time and not licensed in your state I interpret condition of reference monuments with respect to uncertainty as an opinion of pedigree more than anything. Called for, uncalled for, age, original or not, etc. I’m not really buying into your take on it. I’ll bet Gary Kent would know.
Yes, GK surely has an informed and, I consider, a trustworthy opinion/interpretation. I certainly have my own opinion. In reviewing surveys by others, I believe there must be many different interpretations.
Our code does specifically call for an “amount of uncertainty…because of…condition of reference monuments”.
I realize it may be difficult for an LS to interpret state code that is not one where they practice or are licensed, but how would you go about addressing this type of AMOUNT?
Uncertainty doesn’t have to be a 2D linear value, especially with respect to the condition of a monument. A percentage, a letter grade, a high/medium/low rating, all of those things could be used. It looks like they leave it up to the LS to decide.
I don’t like the idea of telling someone a monument that I am holding is uncertain. If I do my due diligence and it’s the best available evidence of the corner, I’m 100% certain that it’s the best available evidence, until proven otherwise.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil PostmanMaybe this will help. I find it interesting that two guys can find a Harrison monument as indicated in a tie report, and one guy says there is “no uncertainty” and the other guy reports an uncertainty of “less than one foot”.
I acknowledge that individual parcels will reveal different levels of dependence on a common monument, but in the case above, I submit that the two surveyors interpret their requirement to offer their opinion on the amount of uncertainty differently.
I would like to see others offer their opinion on how they interpret this issue. Forget what you think my opinion might be…what is yours?
- Posted by: @scott-bordenet
one guy says there is “no uncertainty” and the other guy reports an uncertainty of “less than one foot”.
I’m not licensed yet, but the phrase
“Less than a foot ” is 0.99 feet in law suit land. So it seems that based upon the prior surveyor, based probably upon: historical use, anecdotal data, local customs, and as previously stayed, pedigree, reliance upon etc, that their opinion could be a better option.
The second surveyor IMHO is just avoiding additional work proving how accurate or inaccurate the monument is, cya, blah blah blah..
kind of like if you’re discovering that the section corner you needed for a project and calculated and then searched for, ends up being obliterated or in need of restoration and you avoid doing that work and use a different corner that doesn’t require that much effort.
Again take me with a grain or even a teaspoon of salt.
????
Absent any visible sign the monument was disturbed, or soil that is sliding downhill, it’s hard to imagine that kind of monument getting shoved around. It ought to be within 0.02′ of where it was originally. Pass the salt shaker.
.First, I have no idea what a “Harrison Monument” is.
Second, I would address uncertainty of monument positions in a survey report by quoting the results of a properly weighted least squares adjustment.
Third, a bent monument might have been moved any amount. The bulldozer might have pushed the entire mound of dirt, monument and all, any distance (indeed, any monument might be so moved without being bent, and appear to be in perfect condition when found). So I can really only report on the position as found, and not relative to where it might have been in the past except by comparison to record measurements.
They appear to be cast iron with intentionally weak segments to allow the lower portion to remain in place if the top is struck.
https://www.harrisonmarker.com/products-pricing
.Interesting question. I would approach the conditional uncertainty as a matter of subjective professional opinion and be more inclined to write a narrative than to assign a numerical value to it, e.g. something like Found upright and bent reference monument that appears to be disturbed or relocated due to evidence x,y,z. I guess if I felt confident in assigning a numerical value, I would do so, but I can’t imagine that many scenarios where I’d know with high degree of certainty.
I don’t disagree with your answers – I like them. But, I am going to play devil’s advocate here. The code says to offer an opinion on the amount of uncertainty… How would you do that to meet the code is what I am interested in.
@norman-oklahoma
I am going to play devil’s advocate here (not picking a fight ???? )…
(1) Bill93’s comment is correct about what a Harrison Monument is. Around here, it is a metal monument with cap set in concrete. Think, “the gold standard” or “as good as it gets”, you know, short of the original stone with cut “X” that has been guaranteed to have never, ever moved and protected behind velvet ropes since the day it was originally set ( ???? ).
(2) (Devil’s advocate here) You are describing a measurement accuracy by Indiana code. I don’t care how well you can measure with a 1 second gun and the latest GPS equipment using proper techniques and adjustments. I am sure it is gnat’s ass.
(3) A bent monument situation is an easy issue. We can estimate an amount (linear distance, coordinate displacement) of “bend”.
Consider this: I hand you a tie sheet. In addition to the ties (that are reasonably correct), it describes the original stone monument set in 1820, a call in a legal survey in 1857, a call to an iron pin in 1920, a call to a rail road spike over iron pin in 1957, call by a local surveyor in 1972, a harrison monument set in concrete in 1990 by county surveyor, and the harrison monument being reset in 2012 for road repavement by county surveyor. Norm, you did pull up the right section of code. So now I ask you: give me your opinion as to the AMOUNT of UNCERTAINTY due to the availability and condition of this monument as required by code. Also, how would you formulate this. I am interested in your personal approach.
Yes, I do agree that a written description of its found condition is the best approach. In the end an opinion as to the amount is called for. I agree with you that the issue of certainty in the issues stemming from availability and condition is difficult. I haven’t been personally monitoring that section corner since 1820 when it was set!
See Norman Oklahoma’s reference to the code requiring an opinion on the amount of uncertainty. Some surveyor’s around here will offer an opinion on the amount for each issue of A, B, C & D. Some will offer an opinion on one amount that represents the sum/total of issues A+B+C+D.
How would YOU seek to arrive at amount stemming from A alone?
@scott-bordenet
The statute gives four items that could contribute to uncertainty. I would address relative positional accuracy with LSA as @norman-oklahoma mentioned upthread. That’s an amount that is easily calculated, as well as unambiguous and objective.
But without a clearly defined and objective way of quantifying uncertainty for the remainder of the three, all I can do is offer qualifying statements. I don’t get the impression that the statute requires a numerical value for those three, but it requires the surveyor to explain his opinion with respect to each. That ought to be good enough for anyone following after me.
If someone were to file a complaint and I get hauled in front of the Board, I’d ask them where to find the equations for computing uncertainty at the two-sigma confidence level for monuments based on condition. I’d then ask what numerical weight I should assign a board fence versus a landscaping rockery and whether I need to multiply it by the height when computing possession line uncertainty.
I have Ghilani’s Adjustment Computations to reference for least squares. It relies upon mathematics and statistics, which are proven, universal and objective. If someone questions my relative positional precisions, I can show them how I arrived at my values, and they can crunch the numbers themselves, apply the same equations, and come up with the exact same answer.
Without an equivalent resource for the other three items, any number that you or I throw out there is meaningless. I’d want to see a Board opinion on the matter before I start doing so.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman- Posted by: @scott-bordenet
Consider this: I hand you a tie sheet. In addition to the ties (that are reasonably correct), it describes the original stone monument set in 1820, a call in a legal survey in 1857, a call to an iron pin in 1920, a call to a rail road spike over iron pin in 1957, call by a local surveyor in 1972, a harrison monument set in concrete in 1990 by county surveyor, and the harrison monument being reset in 2012 for road repavement by county surveyor. Norm, you did pull up the right section of code. So now I ask you: give me your opinion as to the AMOUNT of UNCERTAINTY due to the availability and condition of this monument as required by code.
Assuming no record to the contrary I’m going to have to assume that all those surveyors did their work competently and in good faith, and therefore “Harrison Monument’ that currently exists is in the exact same position as the original stone. I do so knowing full well that the position has danced around to some degree, but that there is no way to determine to how much that might be. Again, this assumes that there is no contradictory evidence.
I like your answer. I often ask myself if what I do will pass the “red face test”. Will I be embarrassed to support what I did in front of my board if brought before them.
@norman-oklahoma
So you STILL won’t offer an opinion as to the amount?!?!?
OK – In the spirit of debate and good dialogue, I am admittedly trying to baiting you ???? . I am not as much interested in seeing who will and who won’t state an amount, but why they will or won’t.
- Posted by: @scott-bordenet
So you STILL won’t offer an opinion as to the amount?!?!?
I thought I did. The error is zero. The replacement monument occupies the exact position of the original.
@norman-oklahoma
You state: “The replacement monument occupies the exact position of the original.”
As you stated earlier, we are assuming that previous surveys and work were done correctly (unless not observed to be the case) which we are allowed to do. Also, case law does back this up.
Is this why you are willing to make that statement? Care to add anything?
It does not matter. The requirement is a joke. Ignore it.
Seriously, no one else has any higher knowledge of that monument than you, with the possible exception of the most recent surveyor who has used it. Words are just words. Most of the time they are totally unenforceable. Stop worrying and move on.
We had a Statute for decades dictating the outer boundaries of a subdivision plat must have monuments set in concrete. Possibly one in twenty such plats from that time frame have any concrete whatsoever surrounding the monuments that were set. Generally, no more than a coffee can-sized mass of concrete, which is of little value to stabilizing things. Those can be dug up easily and moved some number of feet by a landowner in the early stages of development.
I am with you – when something is poorly worded (or maybe poorly interpreted by me) and doesn’t make sense, I’ll override the rule. Sometimes I read our rules and say why? Like RPA, you want me to do a LSA or tie into a higher order survey for this????
It is strange to me to see the error some report in this section (how did you come up with that?)…and yet I can’t bring myself to say there is no error in a monument. Lately, I just describe the condition of the monument (found at surface in good condition) and simply state that the error is assumed to be limited to measurement tolerances (see Section D, Relative Positional Accuracy).
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