Accuracy Statements

[Jay Wright]

This thread is a continuation of the thread in which Orange County invited people to join their meeting with the President Elect and discuss
some of the ideas they proposed for changes to the LS Act.
For those not familiar with the issue a little overview, the following was presented for the February Board of Directors meeting

PROPOSED ADDITIONAL LANGUAGE FOR Land Surveyor’s Act
8761(g) Any licensed land surveyor or civil engineer authorized to practice land surveying shall
include a statement regarding the measurement accuracy of the measured data being presented
pursuant to Sections 8726 and 8761. The statement will include one of the following:
(1) Identify the specific procedural specification and publication source used for as the basis of
collecting the data.
(2) Identify the relative positional precision, including statistical confidence, of field measurements
made and represented.
8764(h) Statement regarding specific procedural specification and publication source or relative
positional precision and statistical confidence pursuant to Section 8761(g).
PROPOSED MODIFICATION OF LANGUAGE
8786 The state and any city, county, city and county, district, and special district that accepts any
maps, plats, reports, descriptions, or other documentary evidence invoking the practice of land
surveying as described in Section 8726, shall report to the board any document so received that
fails to identify thereon the person authorized to practice land surveying pursuant to Section 8761,
or that fails to include a statement of accuracy pursuant to Section 8761(g)


As I am a (junior) director I presented this to the chapter at our January meeting for guidance on how to respond.
I voiced my own opposition for reasons I will happily address more fully later.

At the February BOD meeting I reported near unanimous opposition to the idea from our Chapter. I was far from alone in this.
Many other directors reported discussing the idea with members who had vehement opposition to the idea.
In my opinion the idea was on its way to a dismal rejection.
At this point someone, who I believe was a supporter, moved to table the item for a later date and the motion to table passed.

After this BOD meeting in which the idea was tabled, the Chapter had its February meeting which Drexyl attended.
I reported that the idea had been tabled during my report on the BOD meeting. The issue was not discussed in
detail as it was old news. Perhaps it was dinner conversation (remember those days?) as far as "quick and dirty surveys" or who told him it would double the cost of a survey.
I do not recall hearing anything like that and I don't agree with it.

After the idea had been tabled the proponents of it began marshalling support for it, giving a webinar and probably other outreach efforts.
The idea was taken of the table at the November BOD meeting and was passed on to the Legislative Committee for them to edit the language and
bring back up at a future BOD meeting to be voted on.

This item will be back and reasoned opinions based on the preliminary wording above can only help your directors and the Legislative Committee.

[Jim Frame]

My sense is that the people who know how to design and use their measurement systems (hardware + software + wetware) already protect the public by performing at or above the standard of care, and that those who don't have that knowledge will grab a boilerplate accuracy statement, slap it on their drawing template, and never look back. So who benefits from this proposal?

[mpallamary]

For many years, ALTA surveys have required that an accuracy statement be satisfied. In nearly 50 years of surveying, I was asked by only one client to provide the support data to demonstrate compliance with these standards. I was able to do that as all my work assures compliance with these standards as that was how I was trained and educated.

Jim is correct. What folks will do is extract some data file, produced by an equipment manufacturer, that will support this compliance. Needless to say, depending on the algorithm used, a challenge to these standards will be technically difficult, absent some specific rule, theory, or methodology. As most everyone will simply punch some computer program, they will be able to prove compliance (whether it exists or not).

I do like the idea of having surveyors be responsible for preparing survey documents. Every day it seems, this is a problem. Twice this week I ran into situations where a designer, in one case, and in another, a city employee prepared documents that I believe constituted land surveying. They got away with it and in both cases, we are headed to litigation.

As opposed to creating more rules and regulations and reasons to get in trouble, why don't we focus on protecting the practice of land surveying?

Other than that, happy holidays to all. Be safe.

[RAM]

as a Co. Surveyor I have several issues with 8786. This will just add another layer to map check review, and cost. Why? What is the purpose? How do i verify your statement? Am I going to see maps that are to the foot? Im thinking this will be seen as a another reason to not file when my goal is to simplify the process to promote the filing of more maps.

I have seen maps that I dont care for, but met the techincal requirements, follow standards of practice and it is THEIR Map and opinion, if they think they can defend it, have at it.

well, that said, i reread the proposal which states i have to verify the person preparing is a PLS and has a accuracy statement, but i think my rant still applies.

Now i have to think.

[mpallamary]

ALTA STANDARDS:

How many people will swear on a stack of bibles that they follow and meet these requirements?

************************************************************************************************************

E. Measurement Standards - The following measurement standards address Relative Positional
Precision for the monuments or witnesses marking the corners of the surveyed property.

i. “Relative Positional Precision” means the length of the semi-major axis, expressed in feet or
meters, of the error ellipse representing the uncertainty due to random errors in
measurements in the location of the monument, or witness, marking any corner of the
surveyed property relative to the monument, or witness, marking any other corner of the
surveyed property at the 95 percent confidence level. Relative Positional Precision is
estimated by the results of a correctly weighted least squares adjustment of the survey.

ii. Any boundary lines and corners established or retraced may have uncertainties in location
resulting from (1) the availability, condition, history and integrity of reference or controlling
monuments, (2) ambiguities in the record descriptions or plats of the surveyed property or its
adjoiners, (3) occupation or possession lines as they may differ from the written title lines, or
(4) Relative Positional Precision. Of these four sources of uncertainty, only Relative
Positional Precision is controllable, although, due to the inherent errors in any measurement,
it cannot be eliminated. The magnitude of the first three uncertainties can be projected based
on evidence; Relative Positional Precision is estimated using statistical means (see Section
3.E.i. above and Section 3.E.v. below).

iii. The first three of these sources of uncertainty must be weighed as part of the evidence in the
determination of where, in the surveyor’s opinion, the boundary lines and corners of the
surveyed property should be located (see Section 3.D. above). Relative Positional Precision
is a measure of how precisely the surveyor is able to monument and report those positions; it
is not a substitute for the application of proper boundary law principles. A boundary corner or
line may have a small Relative Positional Precision because the survey measurements were
precise, yet still be in the wrong position (i.e., inaccurate) if it was established or retraced
using faulty or improper application of boundary law principles.

iv. For any measurement technology or procedure used on an ALTA/NSPS Land Title Survey,
the surveyor shall (1) use appropriately trained personnel, (2) compensate for systematic
errors, including those associated with instrument calibration, and (3) use appropriate error
propagation and measurement design theory (selecting the proper instruments, geometric
layouts, and field and computational procedures) to control random errors such that the
maximum allowable Relative Positional Precision outlined in Section 3.E.v. below is not exceeded.

v. The maximum allowable Relative Positional Precision for an ALTA/NSPS Land Title Survey is
2 cm (0.07 feet) plus 50 parts per million (based on the direct distance between the two
corners being tested). It is recognized that in certain circumstances, the size or configuration
of the surveyed property, or the relief, vegetation, or improvements on the surveyed property,
will result in survey measurements for which the maximum allowable Relative Positional
Precision may be exceeded. If the maximum allowable Relative Positional Precision is
exceeded, the surveyor shall note the reason as explained in Section 6.B.x. below.

[RAM]

When i have done an ALTA, yes i have.

[mpallamary]

Excellent!

[Randy Mayer]

I agree with Jim's position that we are already required to practice within a standard of care. This cumbersome addition to the Land Surveyors' Act will be difficult to prove and a waste of everyone's time in trying to do so.

[mpallamary]

Not to mention the eventual request by County Surveyors to raise their fees to cover the costs to check maps.

[Dave Lindell]

It's a good thing our equipment is smarter than we are!

[TTaylor]

Way back when I was the chair of the legislative committee, the committee worked hard to get 8726 (n) added to the LSAct. There was some opposition, mostly from CELSOC (at the time) until we included a watered down version that says nothing in the PE Act.

8726
"(n) Renders a statement regarding the accuracy of maps or measured survey data."

As I recall we worked to get this into The LSAct to combat the encroachment of GIS folks producing maps that should be produced by a Land Surveyor. It is virtually impossible to stop maps from being produced, just look at Thomas Brothers. However, If a map contains an accuracy statement then it must be produced by a Licensed Land Surveyor.

I, personally, don't have a problem with "proving" my surveys as statistical indicators are what we look at anyway when processing survey data to determine the precision quality of field work (minimally constrained least squares adjustment) and a fully constrained adjustment to determine accuracy for geodetic and control surveys.

That having been said, I have encountered a number of professional surveyors over the years that feel that by getting the LS License they are now recognized as proficient enough to make decisions on the procedures both field and office in conducting whatever type of survey they are in responsible charge. In other words, if everything is cookbook why would you need a licensed professional?

Finally, IMO this is another example of working towards a solution to a very real problem that in a perfect world would be handled through enforcement of the LSAct by BPELSG.

2 cents

[mpallamary]

Well said,

If I may, and with all due respect to the objectives of this idea, it is rather antiquated. I have been surveying for 50 years, and I began work in New England. We had temperature ranges of 100 degrees and no electronic surveying equipment. We used tapes and plumb bobs and tension gauges when measuring. Back then, it took skill to get a 1/20,000 closure. With advances in modern equipment, it is relatively easy to attain precise measurements. The equipment solves most of those problems. Other than bragging rights to owning the "GPS Model, 2500X, dual resonating, celestial range monitoring, survey equipment," it appears as if measuring capabilities are pretty good.

In the fields of science and engineering, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's true value. The precision of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results. Although the two words precision and accuracy can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.

I guess the question is, what are we trying to accomplish? I was involved in a dispute, years ago, regarding the survey methodology I used to make the measurements. The opposing surveyor was very critical of my survey procedure because I did not place state plane coordinates on my points. The problem was, he located the wrong monument and was off by five feet. He went on and on about the quality of his measurements but it meant nothing. He used the wrong monument.

I think it important that this discussion distinguish between the two. What is the objective here?

Be safe, all.

[hellsangle]

Spot on, Michael !

Do we want to push the profession towards "expert measurer" or forensic retracement? The worst of us are accurate, because we're all using, more or less, using the same equipment.

Like you said . . . what good is the "expert measurer" when he/she can't find correct evidence?!

Stay safe 'n have a good weekend, all.

Crazy Phil - Sonoma

[mpallamary]

It would be interesting to watch an argument between surveyors over the accuracy of their work. Given the efficacy of modern surveying equipment, how much of an ellipse would they be arguing about, especially if the analysis was done by a computer program.

The attached article was written about the same surveyor who criticized my for not using state plane coordinates.

[bryanmundia]

I think that the point of the proposed legislation is being missed in regards to this topic. As I understand it, one of the main reasons for this proposed legislation is really to stop surveyors from setting monuments or performing other surveying tasks using RTK/RTN when that method falls far outside the standard of care for that particular function. I think that in the case with most topics on this forum, there really is a "preaching to the choir' mentality. Most of the surveyors I have had the opportunity to interact with on this forum are the ones who are engaged in the profession and wanting to learn more about surveying as well as seeking professional help in regards to complex surveying issues. They aren't the ones going out and doing a two monument survey to establish 40+acres of land described in a deed from 1920. But to that fact, how many people contribute on this forum? My conservative estimate is around 100. How many licensed surveyors are currently active and working in the state? I don't have the exact number but lets just say 2500 for numbers. That means that only 4% of our profession is engaged in a forum like this. Where are the other 96% and what are they doing to where they have never had the need to even post a simple question or response to their fellow professionals about work they are performing?

Now, to answer the statement/question of "who cares and is it really protecting the public"? I think the answer is yes. As a surveyor, how nice would it be to pick up a map/plat and have a statement from the surveyor who performed the work telling you, the map read, how the monuments he/she found were occupied? A narrative of that fact would prove very valuable to someone like me who is re-tracing the boundary or the neighboring property. If mapping accuracies aren't needed then why do we have them all together? If we took the position of "all surveyors take the same standard of care as I do" mentality and ran with it, do you feel as comfortable as you would knowing the methods and procedures they used to locate the monuments shown on their survey? I take it a step further, if we all take the same standard of care, why do we show boundary establishment notes? With that mentality, we would all weigh the same options and re-establish a boundary the same way right?

Now for the statement in regards to increasing costs to County Surveyors review. I watched a wonderful webinar regarding records of survey recently and took away some valuable insight and methods of thinking that I really didn't consider before. Section 8766 of the PLS Act is very specific about what the County Surveyor can and cannot check/comment on in regards to your record of survey. Unless Section 8766 was revised to include the review of an accuracy statement, the County Surveyor really can't say much about it unless you have a spelling error. They can put a note on your map disagreeing with your standard of care but you can rebut and really that is the last straw right?

For the additional work required of the land surveyor performing the work, I really don't think it adds any time to the preparation of your map. Adding a statement and pulling information from your least squares adjustment software or whatever flavor of adjustment you do on your field work isn't hard to do in this day and age.

The hope with this proposed legislation isn't there to bash on surveyors or give someone another reason to report them to their local JPPC or The Board. It is there to hopefully spur education on the topic and get surveyors talking about their methods of measurement.

I leave you with two examples:

1.) There at one time was a surveyor (not licensed but wanting to be licensed) who was out in the field using GPS. They were at a point in the project where we could not receive corrections or dial up for RTN (i.e. autonomous position was the best they could do). This field crew member was standing over a point and kept pushing the "here" button on the controller. When asked why he said "oh, you see how the coordinates keep changing. Well if you keep pushing the "here" button enough times you will get your true coordinate values because each time you push the button it is correcting." This was something that was "taught" to him by another licensed surveyor while he was working at another company.

2.) While working on a project that required an extremely high level of accuracy and precision both horizontally and vertically we had a field crew come off of a benchmark that had an elevation of 10.05' and level through a number of control points set by another company over the length of the project. Our crew painted (in chalk) the elevations of each benchmark they leveled through after they made their adjustments in their level notes to the same precision as the original bench mark they came off. The next day, a "surveyor" came through with RTK and crossed out our elevations and spray painted the following on one of our bench marks "11.0015". When asked why, he said that is what the instrument gave him on the controller for the value and that is what should have been painted.

Now after reading I ask that you take a deep breath and don't let your eyes roll too far back in your head but this is what we are dealing with and this is what needs to change.

[Edward M Reading]

Bryan,
Your two examples make the case for an educational requirement, not an accuracy statement.

[mpallamary]

Hello Bryan, I hope this notes finds you well and safe. Your comments are in line with my thoughts and your observations are valid. I, too amy trying to figure out the goal. Assuming we are not talking about geodetic work, where is this headed?

Per above:

1) Identify the specific procedural specification and publication source used for as the basis of
collecting the data.

(2) Identify the relative positional precision, including statistical confidence, of field measurements
made and represented.

8764(h) Statement regarding specific procedural specification and publication source or relative
positional precision and statistical confidence pursuant to Section 8761(g).

It would be helpful, at least for me, if someone can provide an example as to how items 1 and 2 would read. Assuming there are a hundred ways to answer these questions, or posit language, does anyone have prescribed or preferred language? As opposed to every surveyor making things up, would it not be better to proffer the answer more like a form instead of people making their own statements up?

What is an acceptable confidence level? Should it vary from rural to urban property?

Do we agree:

“Relative Positional Precision” means the length of the semi-major axis,
expressed in feet or meters, of the error ellipse representing the uncertainty due
to random errors in measurements in the location of the monument, or witness,
marking any corner of the surveyed property relative to the monument, or
witness, marking any other corner of the surveyed property at the 95 percent
confidence level (two standard deviations). Relative Positional Precision is
estimated by the results of a correctly weighted least squares adjustment of the
survey.

The attached discussion may be helpful.

https://cdn.ymaws.com/www.mnsurveyor.co ... zelton.pdf

As always, I think constructive dialogue is a good thing.

[Jay Wright]

I recall from the webinar that this is not meant to be a requirement to use least squares on every description, plat, etc.
At that time an offer was made to visit a website that had some spreadsheets and other data for those concerned with that aspect.
I will find my notes and share the link if no one objects to that idea.
I am sure some of that subject matter is worth reviewing regardless of the outcome of this proposal.

Some people, who do not seem to be confused by the arithmetic, are asking what benefit a surveyor would derive from this requirement.
Will it in any way enhance your/my efforts to retrace my/your survey?
If this passes, the accuracy statements on every Corner Record or Record of Survey with the statement on it would probably be read pretty closely at first
until the rest of the survey community gives up and just copies and pastes mine.(that's right, I said it)
After that we just need to get the sheet size requirements changed andit will have no practical effect on business.

[mpallamary]

Indeed!

[mpallamary]

The maximum allowable Relative Positional Precision for an ALTA/ACSM Land Title
Survey is 2 cm (0.07 feet) plus 50 parts per million (based on the direct distance between
the two corners being tested). It is recognized that in certain circumstances, the size or
configuration of the surveyed property, or the relief, vegetation or improvements on the
surveyed property will result in survey measurements for which the maximum allowable
Relative Positional Precision may be exceeded.

[mpallamary]

‘Absolute’ precision is usually considered to be the
precision of a point with respect to some datum, e.g.,
NAD 83
This really means the precision with respect to the
center of the Earth
This will include all measurements and their errors to
get to you from the datum point (this may be large)

[mpallamary]

As will be appreciated, ‘absolute’ precision is of little use for a local survey, even though it may be available
Two nearby surveys of comparable quality may have radically different ‘absolute’ precisions, owing to
different connections to the datum, which were not done by the surveyors doing the actual jobs
So we use ‘Relative’ Precision instead for small surveys

[mpallamary]

Note that ‘Relative’ Precision is NOT Local Accuracy, which requires more complex calculations
Relative Positional Precision is how repeatably pairs of points are positioned with respect to each other within
a single survey This can be determined using positional error ellipses in an unconstrained adjustment, as one approach

[mpallamary]

If we fix a single point in a survey network, so its adjusted precision equals zero, the error ellipses of the other points
show the relative precision with respect to the fixed point This allows a quick and simple estimate of the relative
position of all points with respect to just one What about relative precision with respect to other points?

[mpallamary]

Accurate, precise: The shooter again assumes a prone position, rests the barrel of the rifle on a support, takes careful aim, holds his breath, and gently squeezes the trigger four times. This time, the four holes are very close to the center of the target (accurate) and very close together (precise).

To illustrate the distinction between terms using a surveying example, imagine surveyors very carefully measuring the distance between two survey points about 30 meters (approximately 100 feet) apart 10 times with a measuring tape. All 10 of the results agree with each other to within two millimeters (less than one-tenth of an inch). These would be very precise measurements. However, suppose the tape they used was too long by 10 millimeters. Then the measurements, even though very precise, would not be accurate. Other factors that could affect the accuracy or precision of tape measurements include: incorrect spacing of the marks on the tape, use of the tape at a temperature different from the temperature at which it was calibrated, and use of the tape without the correct tension to control the amount of sag in the tape.