Accuracy Statements

[DWoolley]

as I review this thread, it reminds me, 1 size does not fit all. Many here talk about, 0.05', 0.10' but in my world that type of measurement is not realistic when surveying parcels of 5 ac. and up, over topographically challenging terrain. Are folks actually using the methods with their instrumentation to achieve what they claim? In I survey 1000' with an elevation change of 500', tie with RTK, am i within 0.10'? Most private work will not pay to achieve that result.

I second Bryan's observation, a monument is a monument. Surveying is much more that measuring.

RAM:

The 0.10' is the best case scenario - using RTK with an onsite base to minimize the PPM error. On a 1000' measurement of a line it would be a 1:10k precision (1000'/0.10') survey. During the course of a survey (i.e. elapsed time) the measurements will vary as much as 0.3' min/max horizontally, being 1000'/0.4 being 1:2300. Can everyone see why the next surveyor would like to know how the project was surveyed? Frankly, a surveyor could say they guessed the distance, fine, just state so on the work product.

RAM, out of curiosity, why not use static GPS? In my experience, if I set up the unit first, then describe the monument in my notes, take the photos, enough time has elapsed to have the information to post process a good solution.

Lastly, what is meant by "Most private work will not pay to achieve that result"? My thought is a client has no sense of a land surveyor's measurements tools.

Randy Mayer, amen, agreed.

Keith Nofield, the polls on this website are worthless. There is usually less than 20 replies and the polls are not representative of the 4000 licensees or even, the 150 or so people that read this forum, totally worthless.

DWoolley

[TTaylor]

IMO,

GPS for boundary surveys would be best as fast static or static with s typical network type design using independent baselines, redundancy, and "cross ties".

If RTK is used then a " calibration" (local site transformation) should be used constrained to the monuments controlling your survey.

2¢

[Jim Frame]

GPS for boundary surveys would be best as fast static or static with s typical network type design using independent baselines, redundancy, and "cross ties".

A lot depends on what kind of boundary survey you're talking about. I wouldn't dream of using RTK to survey an urban/suburban lot (except see below), but if I'm breaking down a section -- or spanning multiple sections -- I can usually do better with a couple of redundant RTK observations than I can with a total station, and in a fraction of the time. The difference between redundant RTK and static in these situations isn't generally significant.

Urban/suburban exception: I *sometimes* use RTK to locate monuments on the far side of a modern subdivision block as a check against a large deviation from record. If the RTK positions check at the tenth-or-less level I may be content to skip traversing around the block, which can result in a large savings in time/cost. The decision to use this approach depends on the purpose of the survey; marking corners for fence construction generally gets a different treatment from marking corners in anticipation of a court battle.

[steffan]

Close enough? Accuracy? See attached. Reality is this is hecka common in different forms.

[TTaylor]

I agree, Mr. Frame.

Land surveying decisions depend on the scope and the intended use of the results.

Again (I repeat myself) any reported "accuracy" of a boundary survey should be relative to the original "meter" used to initially establish the Boundary.

[PLS7393]

At last nights SC/SM Co Chapter meeting, this topic appears to be gaining speed again.
Why do we need this or even an attempt? It was shut down once earlier this year in 2021, so who is behind this to bring it up again?

[falcon]

I personally am against it and so is much of my chapter. However if I recall correctly the item was tabled and the people that brought it were going to work on the language and try to convince others of it's utility through a webinar. Which I didn't attend so can't comment on.

[DWoolley]

At last nights SC/SM Co Chapter meeting, this topic appears to be gaining speed again.
Why do we need this or even an attempt? It was shut down once earlier this year in 2021, so who is behind this to bring it up again?

The CLSA Board of Directors, representing the 22 CLSA chapters, voted in February 2021 to move forward on an accuracy statement. I believe the vote was 92% in favor of the idea. See the CLSA minutes for the exact motion.

To answer the second question, the CLSA Board of Directors is behind the idea that originated in the Orange County chapter. There is an entire discussion as to the reasoning. Many folks that do not like the idea see the necessity of moving it forward.

I am interested in any other ideas to distinguish land surveyors from other measuring tradesman i.e. carpenters, contractors, plumbers, laborers etc. that continue to use technology to displace the professional community.

More importantly, there is a huge safety component with the implementation of SB865 - which requires asbuilt locations of underground utilities to a specific accuracy. Who else can determine the location of the utilities to the specifications to provide the public assurances as to line location?

DWoolley

[steffan]

More importantly, there is a huge safety component with the implementation of SB865 - which requires asbuilt locations of underground utilities to a specific accuracy. Who else can determine the location of the utilities to the specifications to provide the public assurances as to line location?

DWoolley

Dave,

Looking at SB-865 I only see the following enabling language:

(5) Commencing January 1, 2023, all new subsurface installations shall be mapped using a geographic information system and maintained as permanent records of the operator.

Am I missing something? I'm not seeing where the law requires utility installers to capture their as-built data to any sort of accuracy.

While the author's intent with this portion SB-865 would seem to warrant actual accurate information, the reality appears to be more of a cartoon product.

[LS_8750]

The PLS Act includes geodetic work.
The PE Act excludes geodetic work.

Do the geologists and geophysicists have geodetic positioning work in their scope? I haven't looked.

I hear a lot of talk about centimeter accuracy and survey grade accuracy. What does that mean? Are we taking into account grid vs ground? Are we talking about the ppm +/- accuracy of our total stations against those blurry aerial crosses from a drone image, or a shag carpet lidar point cloud?

What about the influx of new satellite datasets doing millimeter change detection?

Most folks outside of, and probably quite a few in side of, the land survey community have never heard of or contemplated such matters.

So sure, something needs to be addressed.

[mpallamary]

With all due respect for this discussion, we are dancing on the head of a pin. Why is CLSA focusing on this topic when the existing rules and laws are not being respected and we are losing ground every day to 5th graders flying drones around and 7th graders making maps?

Why isn't the state board and CLSA protecting practice and profession.

I can't wait to see how a complaint is going to go when two surveyors are arguing over a least squares adjustment and someone files a map calling the other surveyor off by 0.02 feet.

What are we doing and why?

[ekparian]

Mike,
I agree. I feel we can do better protecting our profession in other ways.. example: by enforcing the filing of record of surveys and holding onto site plans.(off the top of my head.)

Our stamp is what makes us stand out from the rest.

Seems like our board snuck this through without the majority 's knowledge during covid. I remember my chapter not supporting it before covid started.

[Jay Wright]

February Minutes
"Accuracy Statement
Moved and Seconded to send Accuracy Statement issue to the Legislative Committee to work out a recommendation for the Board of Directors to review. Motion Carried"

This was NOT the Board of Directors recommending moving forward on any change to the PLS Act. The Board's action was to take the issue off the table and give the Leg. Com. another swing at it.
I will post about the recent motion in the next couple of days

[PLS7393]

With all due respect for this discussion, we are dancing on the head of a pin. Why is CLSA focusing on this topic when the existing rules and laws are not being respected and we are losing ground every day to 5th graders flying drones around and 7th graders making maps?

Why isn't the state board and CLSA protecting practice and profession.

Well said Michael. Furthermore, Who's on first?

[hellsangle]

. . . and they wonder why some are leaving CLSA . . .

The Three Signs people are trying to run CLSA.

Have a nice Thanksgiving, all.

Crazy Phil - Surveyor to Recorder

[SPMPLS]

. . . and they wonder why some are leaving CLSA . . .

The Three Signs people are trying to run CLSA.

Have a nice Thanksgiving, all.

Crazy Phil - Surveyor to Recorder

Amen, Phil. When people have leaders they don't believe in, they will not follow. A fact of life.

[Jay Wright]

At the latest Board of Director's Meeting this issue was addressed in the agenda in this manner

Addition of accuracy statement to Records of Survey
Motion: Move approval to proceed with revisions to the Land SurveyTor's Act for accuracy requirements by adopting the language from the Nevada Administrative Code NAC 625.651-625.740, or similar standards.

The attached NAC 625.651-625.740 is hereby submitted to the CLSA Board of Directors so the directors can take it back to their chapters for feedback and recommendations.

I didn't attach it here, Mr. Google can find it for you.

During discussion I asked if this was really meant only for Records of Survey and was told this was a mistake in the preparation of the committee report and the intention was not just for ROS maps but I don't recall any specifics as to which instruments would be included or excluded.

[mpallamary]

Alas, whither the wind.

[btaylor]

As someone who is maybe too anal retentive at times, does Star*Net for most jobs like most of us here, etc. etc., I fail to see how this does anything special other than creating a sense of confusion to the public when two surveyors who happen to be very accurate disagree by a foot or more.

The problems I see are not related to whether they used a calibrated rod and are .05' sloppy on their side shots.

Just please make the required text on the ROS maps be limited to a line or two, since the space is limited.

[Edward M Reading]

...
Why isn't the state board and CLSA protecting practice and profession...

While I agree with your points, Mike, the Board's job isn't to protect the practice and profession, it is to protect the public. It's CLSA that should be protecting the profession.
Ed

[mpallamary]

Hi Ed,

Happy holidays! You make a good point regarding the Board and CLSA. Thanks for that! Yes, CLSA should be focusing on things that will better serve the profession. I for one do not believe accuracy standards will do it. I know I am going to sound like an old man but in this case, it has relevance. When I began surveying 50 years ago, we did not have any electronic equipment. The mark of a good land surveyor was proven with their ability to measure and produce a tight error of closure. We were Masters of Measurement. Today, with all the fancy equipment we have, accuracy standards seem like an absurd topic. Virtually everyone measures with sophisticated equipment and most surveyors simply accept the values produced by a computer, or a total station, or GPS. If there is an adjustment, it is so sophisticated, and it is done by a computer applying some exotic algorithm. Is that how they will be checked? By another computer? If so, what are the acceptable programs and equipment? What will be the measurement standards? Will the cost of a Record of Survey double? If your work is disputed by another surveyor, will there be grounds to sue? Are we promoting litigation?

I can hear it now: My Topcon is more accurate than your Leica.

CLSA should focus on non-measurement things like ethics, business practices, law, and interaction with other professionals. If we have the time to
debate accuracy, why don't we have enough time to work on our image?

There are enough angels dancing on this pin.

[mpallamary]

More to consider.

[mpallamary]

If you have children or grandchildren, what is more important? That they know how to add and subtract or, they are honest, ethical, and tell the truth? What is more important? We live in very challenging times. Should we not respond accordingly?

[mpallamary]

I borrowed this picture from my friend Jeff Lucas. All of the monuments in the photo below were located with great precision and redundantly measured a dozen times. Which one, if any, is the most accurate location of the property corner?

I note:

In the physical sciences, variability may result from random measurement errors: instrument measurements are often not perfectly precise, i.e., reproducible, and there is additional inter-rater variability in interpreting and reporting the measured results. One may assume that the quantity being measured is stable, and that the variation between measurements is due to observational error. A system of a large number of particles is characterized by the mean values of a relatively few number of macroscopic quantities such as temperature, energy, and density. The standard deviation is an important measure in fluctuation theory, which explains many physical phenomena, including why the sky is blue.

See also: https://www.amazon.com/Pincushion-Effec ... B009ANB3PO

[TTaylor]

Only random errors should be in measurement analysis with all systematic errors removed.
The key statistical indicator for measurements is the Standard Error of the Mean.

The picture you shared, Mr. Pallamary is an abomination on any number of levels.