Accuracy Statements

[mpallamary]

https://appel.nasa.gov/2006/07/01/a-pow ... ite-paper/

[mpallamary]

From the previous post:

"A white paper allows you to communicate to a wider audience, so people don’t fall victim to the telephone game, and you reach people who are technically capable of criticizing your logic and your data but could not attend your review boards. Ralph Roe of the NASA Engineering and Safety Center couldn’t attend a single one of my review boards, but he provided very effective and useful input through criticism of the white paper and offered recommendations for strengthening our logic. One of his immediate observations after reading an early draft was we had failed to provide a rationale for adequate fatigue life, which is the amount of strain our parts can take before they fail.

We had discussed our fatigue life rationale in many forums, but it didn’t appear on any charts. Neither had we done a thorough job of writing that rationale down. I ended up writing another ten pages to express our logic and, in the process, found that our rationale was actually stronger than we’d originally thought.

Providing folks an opportunity to offer constructive, informed input outside the lengthy and intense technical meetings adds considerable strength to the technical approach to a complex problem. I run forums open to everyone as long as they don’t bring up cost and schedule, but not everybody can engage verbally or devote time to those forums. That’s an important lesson learned for me."

[mpallamary]

Please see the attached to see how they classify things in Texas. I recommend considering using some existing models as opposed to creating a new wheel.

[hellsangle]

I assume there is a "nexus" for this proposed legislation because one surveyor screwed up/

Okay. Pass legislation that affect the entire state?! Give us more-than-one real world examples of the need for this . . . .The-Skies-Are-Falling legislation!

And try give those copious examples in four sentences or less!

Becoming Bah Humbug Crazy Phil

[LS_8750]

Does anybody believe they are actually complying with the ALTA accuracy requirements anyway? How tight are you on those hose bibs, gas meters, trees, utility poles, building corners? Are you measuring to face of fascia, stucco, concrete footing? How is the workmanship of that concrete footing anyway?

The proposed accuracy statement requirement should scare nobody. Why the fuss? Did you actually stop at that stop sign thismorning?
The accuracy statement purpose has been stated clearly by Mr. Woolley.

Instead, how bout we push this through and focus attention on pincushions and those dipshits that don't understand or concern themselves with the rules of evidence? The JPPCs are overwhelmed with the number of cases reported.

[LS_8750]

Actual conversation:
"How tight do you want this?"
"It's only a rocketship launching pad."
"Oh. Ok."

Why did I ever ask?

No catchy accuracy jargon is gonna replace, "Good!" Or "Good enough." or "These clowns will never know the difference."

[DWoolley]

I assume there is a "nexus" for this proposed legislation because one surveyor screwed up/

Okay. Pass legislation that affect the entire state?! Give us more-than-one real world examples of the need for this . . . .The-Skies-Are-Falling legislation!

And try give those copious examples in four sentences or less!

Becoming Bah Humbug Crazy Phil

There is no example of a land surveyor screwing up that drives the need for an accuracy statement. I would encourage you to read the Gary Kent articles Mike Pallamary posted - even if you have to read them four sentences at a time.

Land surveying in California, in the current form, is unsustainable (I have provided reading material, references to books and other examples to support why I believe this to be true). When viewed as a whole, the land surveyors no longer have the skillset or practice in a manner that justifies the need for licensure. The Legislature will ask for examples of unlicensed practice damaging the public – does anyone have the list and examples of damages ready? No. Because the damages, if they exist, are undocumented and the BPELSG enforcement statistics can demonstrate the numbers of lawless land surveyors do not understand or practice in a way that protects the property rights of adjacent owners.

Fortunately, today, we have folks in the community that have the requisite skills to pass onto the next generation to build a sustainable model. Equally fortunate, there is an existing statutory structure, today, in the Professional Land Surveyors’ Act that land surveyors should honor – rather than equivocate and dodge like a bootlegger.

There is not enough demand for the writing of legal descriptions and mapping to sustain the land surveying community – these skillsets, determined by reviewing the local filed maps, make up less than 10% of the current licensed community in Orange County. The accuracy statement is to create a marketable skill that will be used to regulate and monitor the unlicensed practices i.e. construction and topography measurements (each lost land surveying markets). The land surveyors can hone and offer a skillset that is understanding, analyzing, mastering and the documentation of measurement – err, not waving around their 1:100,000 closure. Again, the surveyor will have the option to function similarly to an inspector or resident engineer supervising the trades – as described previously.

Why is there such resistance to learning new skills and creating statutory protections to help safeguard the public and the future of the profession? Rhetorical question. I suppose the farriers, lamplighters and wainwrights of yesteryear had similar “do nothing” or “what could possibly go wrong” plans and practitioners. Death of the profession, like death itself, may be inevitable.

Phil, pick any four sentences. Also, I will offer you a parting gift:

“Well, prince, Genoa and Lucca are now nothing more than the apanages, than the private property of the Bonaparte family”.
…
“Nothing is without consequence, and nothing is important: it’s all the same in the end”.

The first and last sentences of War and Peace – a gift in two sentences. What more could there be of substance? Somehow, it just does not seem the same, less satisfying. It is probably me. You’re welcome.


DWoolley

[Jim Frame]

Does anybody believe they are actually complying with the ALTA accuracy requirements anyway? How tight are you on those hose bibs, gas meters, trees, utility poles, building corners?

ALTA Relative Positional Precision requirements pertain to boundary control, not to feature location. So, yes, I believe I do comply with the requirements.

[hellsangle]

Dave,

You've cited an article . . . but still haven't shown more than one case/example, here in California, that would have us all change California law?

Hope you all had a nice Christmas/Chanukah/Kwanzaa/Festivus holidays!

Respectfully yours,

Crazy ol' Phil

[LS_8750]

Woops.
Well Mr. Frame. Thanks.
What are we afraid of then?

[btaylor]

An accuracy statement on our maps is silly and a waste of needed space on an ROS. It's also backwards, because when this was needed was on the old subdivision maps we are retracing. If I knew ahead of time that the lot corners are accurate to 5 feet on some old map that's nice to know. Knowing I use Star*Net is a nice humblebrag but otherwise a superfluous item to a retracement of a lot on a map. The issue is the old maps, not new ones, when it comes to this issue.

[hellsangle]

How many BPLESG citations has an accuracy as been a problem?.

One less freedom. One more thing for interpretation . . . by County . . . by BPELSG . . . etc.

And how did having the County Surveyor review Record of Surveys work out for us? Which, by the way, such legislation prove to be MORE hoops for (some) County Surveyor's to jump you through!

Crazy Phil again

[DWoolley]

Mr Woolley-
You have said this several times on this thread. My ears perked up the first time I saw it because I have been scratching my head for months about how this proposal was going to affect my Record of Survey. Turns out it doesn't?

Any land surveyor’s work product, including a record of survey, will have an accuracy statement that relates to the field measurements. However, generally speaking, measurement is a much lesser consideration in boundary location determination. The Gary Kent articles articulate the need for accuracy statements.

Are you saying that the accuracy statement only applies to topographic surveys and utility locations? I find this confusing as the placement in the LS act implies to me that it will directly affect our Record of Survey procedures.

The accuracy statement will apply to a land surveyor’s field measurements. This would include boundary mapping, underground utility locations, topographic mapping, construction staking, geodetic coordinate determinations and any other field measurements. The land surveyor will express a quality of the measurements.

Suppose a land surveyor states the measurements are within 0.10' x 0.10' at one sigma, but fails to find the original monument that was placed 2.50' different than the mapped location - monuments hold over map dimensions. The monument controls the corner location and the 0.10' x 0.10' accuracy statement is meaningless as to the actual boundary location, but quantifies the location of the controlling monuments shown.

How will the LS act affect notes or statements on topographic maps and utility locations which are largely unregulated?

The trades, generally speaking, believe most measurements are accurate to 1/16th or an 1/8th of an inch. Why wouldn’t they? Most of their careers have been limited to measuring less, considerably less, than 100’. Land surveyors understand, or should understand, static GPS to be 1 cm and 1 PPM and the why and the how the information is post processed - not the actual 1cm, but the reference frame. The land surveyor understands the 1 cm is meaningless if the information is on an incorrect vertical datum or horizontal epoch. Most trades have no sense of epochs or datums (which often vary by several feet) and therein, rests the land surveyor's professional expertise.

I do not find the excerpt above meaningful

This demonstrates the need to increase our skillset. I like the note, but I would not have put it in terms of semi-major axis. I prefer to give the dX and dY of the largest error. For the record, I made the mistake of using the average error on a couple of maps. The average error is not representative of the work product as the positionally worse-case is not captured in an average. In fact, it is “averaged out” and misrepresents the work product [always learning].

This one includes make and model of total station and GPS receiver and software brand. A previous poster in this thread specifies error ellipses down to .016' at 1sigma.... Nonsense!

The 0.016 at one sigma is the same, within a hundredth, as the 0.06’ on the semi-major axis at 95%. It is the same information written differently.

Can you explain the value of this?

The value is for the land surveying community to hallmark and differentiate their skillset, as a professional skillset worthy of licensure to protect the public from harm. The professional's skillset is different from those of the trades using the same or similar equipment. Also, the value is to create opportunities for the land surveying community to supervise, monitor and regulate the trades.

For the record, the land surveying community and the respective licensing boards have not been successful in curtailing the trades from practicing statutory land surveying. This will not change in the foreseeable future.

Please present some concrete examples of how this will be applied. I have asked four or five times for this information in different venues - board meeting, webinar, email, etc. My patience is waning.

Are you looking for samples of accuracy notes? If so, there have been several posted that serve the purpose. As professionals, the thought is not to prescribe an exact statement, not initially, rather, allow the professionals to make the determination. Discretion is a hallmark of a profession. The accuracy note should include the equipment and procedures.

Off the cuff:

The topographic features shown hereon have been verified by the prescribed methods [next paragraph list those methods] to meet the national map accuracy standards of 1947.

DWoolley

[DWoolley]

How many BPLESG citations has an accuracy as been a problem?.

One less freedom. One more thing for interpretation . . . by County . . . by BPELSG . . . etc.

And how did having the County Surveyor review Record of Surveys work out for us? Which, by the way, such legislation prove to be MORE hoops for (some) County Surveyor's to jump you through!

Crazy Phil again

"Professional regulatory bodies are required in law to protect and promote the public interest by regulating the practice of the profession. The fundamental mission of professional regulatory bodies is to minimize and mitigate the risks to the public that may arise from the practice of the profession." [Random internet source]

Land surveying needs regulation to be recognized as a profession. The more regulation, especially in a regulatory state like California, the more importance is placed on the professional's knowledge and skills. The work is perceived to be so important it needs to be regulated.

Phil, I understand your argument. You are the proponent, the face, of deregulation of the land surveying profession - know this, the wind is in your favor and I like your odds. You are the smart money on this horserace. I find it peculiar that you involved yourself in the professional aspects of land surveying. What prompted the change of heart and resulting push for trade status? Rhetorical question. For the unacquainted, Phil has served in multiple capacities within CLSA, been an active member at the chapter and state level and spent many years as the CalSurveyor Editor.

One less freedom.

"Freedom is just another word for nothin' left to lose" Janis Joplin (written by Kris Kristofferson).

DWoolley

[hellsangle]

I guess I’m still trying to understand your nexus, Dave.

It seems heavy on the “op-ed” than a nexus of facts. I don’t believe the sky is not falling.

An analogy might be California’s helmet law. Kids crash their bikes . . . get knocked off their bikes, etc. and the physical damages can be life long. A nexus for a law.

Another is California’s seat belt law. I used to be a volunteer fireman and when we extricated a person not wearing their seatbelt their injuries were much more serious than those wearing seatbelts. Again, a nexus for a law.

The worry of being deregulated? This is California, Dave! Since when does any of California government make things easier? One of the reasons large and small business' are leaving California! BECAUSE of over regulation.

Just more crap for the County Surveyor to ask for . . . map clutter . . . and “gotchas” in litigation. Be careful what you wish for . . . on the rest of us.

Sorry, I broke my own four-sentence rule. LOL

Respectfully yours,

Rantin’ ol’ crazy Phil

[bryanmundia]

An accuracy statement on our maps is silly and a waste of needed space on an ROS. It's also backwards, because when this was needed was on the old subdivision maps we are retracing. If I knew ahead of time that the lot corners are accurate to 5 feet on some old map that's nice to know. Knowing I use Star*Net is a nice humblebrag but otherwise a superfluous item to a retracement of a lot on a map. The issue is the old maps, not new ones, when it comes to this issue.

At some point aren't these "new" maps going to become "old" maps? You have said yourself it would be nice to know. Don't you think it would be good for future generations of surveyors to have this as you so willingly want on old plat maps?

[bryanmundia]

To Phil and others:

How about this for an example.

Surveyor A goes out and does a boundary retracement on an old lot in a urban area of the State. He/She finds all of the original monuments at the lot corners but only shoots them from nearby traverse points that are used for the loop closure of his/her survey. He/She never occupies the monuments or shoots them from multiple set-ups. They run their adjustment data and find that their control is +/- 0.03' in the Northings and Eastings but since they only located the monuments from a single set-up their positional uncertainty on their boundary corners is +/- 0.15'. In the process of the survey they also set-up on one of the boundary corners and shot a wall along the line. When performing their boundary analysis, they find that the wall (which looks original based on material, character, weathering, etc.) encroaches by 0.2' onto the neighbors property. They file an RS and tell the property owner that the neighbors wall is encroaching by 0.2'.

Surveyor B goes out and does a retracement of Surveyor A's work for the neighbor. Surveyor B occupies each boundary corner, shoots said corners from various setups and closes their traverse. When running their adjustment they find that their control is +/- 0.03' in the Northings and Eastings on every monument, control point, etc. Surveyor B also sets up on a boundary corner and shoots the same wall and finds that it is encroaching by 0.05'. Surveyor B files an RS and lets his client know that the wall is actually on the boundary line.

In this instance has the public been damaged? Does Client A and Client B have something to be angry about?

I have seen this on a number of occasions, especially with those surveyors using RTK or RTN to with 15" observations to occupy boundary corners. Without a written criteria in place, how are we to regulate and govern the work that is being performed?

Example 2:

Pincushion Effect (Need I say more). Without a stated relative accuracy there is actually more of a possibility of a pincushion effect. If I am doing a retracement survey and I find original corners, prorate back in the dividing lot line on a tract and hit a monument along said dividing line within +/-0.15' what am I to do? Well, if I had put a relative accuracy note on my surveying stating that all corners set are within 0.15' then problem solved right? If I didn't I am left to the demise of another surveyor (possibly less competent than myself) to determine if the monuments I set are in fact in the correct location. Whereas if I had a stated accuracy note and that surveyor goes out and measures anywhere between +/-0.00' to 0.15' on the monuments I set, they in fact know that I set this in the correct location and no additional RS is needed or monuments to be set.

Example 3:

Underground utility markings. I call Digalert and have the appropriate agencies come out and mark the location of their underground lines. As owner/builder on my 4 story apartment complex and measure out 2 feet from the marked utility line and begin digging my footings. About 18" down I hit a gas main which causes major delays in construction as well as a costly replacement of a more than likely very expensive utility line. Prior to digging, if I had provided a sketch showing where I marked the utility as well as an accuracy note, stating that the utility lines are +/-2'. Then all of my bases are covered and as long as owner/builder doesn't hit an unmarked line within that 2' buffer, I am good to go. However, if I didn't put that explanation and note on the map, who do you think is the first name in the lawsuit?

On a separate note, I thought it would be interesting to put into the google machine the following "state laws regarding relative accuracy for land surveying". The fascinating thing is that this isn't a new topic or one without legs. There are quite a few states in this land of the free that have mandated relative accuracy requirements for land surveying practices. Albeit, some states are more thorough than others, but nonetheless these laws do exist in alot of states, including the Western United States. Why is California behind the times with this, especially with the high cost of land in this State?

[mpallamary]

Is it possible that what is really being discussed is Quality Assurance and Quality Control (QA & QC). Far too many surveyors (and engineers) fail to implement a good QA/QC program.

If you look around, you will notice that many states have defined varying surveying standards for various types of surveys. At this time, given the aversion to legislation, would it not be preferable for CLSA to adopt some preferred standards that the association and its members can embrace such as:

"This survey meets or exceeds the technical standards for a (boundary survey, construction survey, elevation survey, control survey, GPS survey - pick one) as published by the California Land Surveyors on June 1, 2021."

ALTA standards have evolved over the years to address changes in technology or methodology. I sense the same thing is occurring here.

I, for one, would welcome some standardization of survey methods and procedures. The state of surveying and particularly data gathering is rather pathetic. There are a lot of measuring people out there who push buttons while drinking a cup of coffee, and far too few surveyors.

[btaylor]

An accuracy statement on our maps is silly and a waste of needed space on an ROS. It's also backwards, because when this was needed was on the old subdivision maps we are retracing. If I knew ahead of time that the lot corners are accurate to 5 feet on some old map that's nice to know. Knowing I use Star*Net is a nice humblebrag but otherwise a superfluous item to a retracement of a lot on a map. The issue is the old maps, not new ones, when it comes to this issue.

At some point aren't these "new" maps going to become "old" maps? You have said yourself it would be nice to know. Don't you think it would be good for future generations of surveyors to have this as you so willingly want on old plat maps?

To surveyors 100 years from now reading this:

Consider my marks accurate to .02' in case you can measure to .0.00008'.

Just remember, future surveyors, when looking for my pipes, you need to generate a much greater seach area than you are used to. You may not be able to find them otherwise.

[PLS7393]

How about this for an example.

Surveyor A goes out and does a boundary retracement on an old lot in a urban area of the State. He/She finds all of the original monuments at the lot corners but only shoots them from nearby traverse points that are used for the loop closure of his/her survey. He/She never occupies the monuments or shoots them from multiple set-ups. They run their adjustment data and find that their control is +/- 0.03' in the Northings and Eastings but since they only located the monuments from a single set-up their positional uncertainty on their boundary corners is +/- 0.15'. In the process of the survey they also set-up on one of the boundary corners and shot a wall along the line. When performing their boundary analysis, they find that the wall (which looks original based on material, character, weathering, etc.) encroaches by 0.2' onto the neighbors property. They file an RS and tell the property owner that the neighbors wall is encroaching by 0.2'.

I say bad example, why?:
1) If a surveyor doesn't set up on a monument and back sight another, . . .garbage in, garbage out. Accuracy statements won't fix that bad practice but formal complaints may open the eyes of that surveyor. But then formal complaints go through interpretations, and don't get me started on interpretations as I believe there are other threads for that.

2) You state a 0.15' positional uncertainty on boundary corners, and the wall encroaches 0.2'. I see that as potentially only a 0.05' difference and acceptable for for construction tolerance. A tolerance statement won't fix that. An education and survey sense will go a lot further in the survey profession.

I have seen this on a number of occasions, especially with those surveyors using RTK or RTN to with 15" observations to occupy boundary corners. Without a written criteria in place, how are we to regulate and govern the work that is being performed?

Again I disagree with this example, because how good of a surveyor are you if your using RTK (with a network) for boundary work? Same goes for these guys using RTK for monument preservation, and listing coordinates to the 0.01'. Again my interpretation is garbage in, garbage out, but hey they are using expensive equipment so it must be good. Looks good to the public too, but the tolerance statement on maps won't fix the real problem.

If the proposed tolerance language goes through, might as well outlaw the use of robotic stations too. That is the No. 1 cause for the lack of any mentoring program for the younger surveyors to really learn, and not from a book. Now we all are all bout the numbers, and not "Real Surveying". Too many damn coordinate surveyors out there, and this proposed language proves it. I'm going back to a Transit and Chain, +/- 1' to follow in the footsteps of the original surveyor.

Phil, I understand your argument. You are the proponent, the face, of deregulation of the land surveying profession - know this, the wind is in your favor and I like your odds. You are the smart money on this horserace.

3) I got $500 on Phil!!!


HAPPY NEW YEAR ALL!!!

[Jim Frame]

1) If a surveyor doesn't set up on a monument and back sight another, . . .garbage in, garbage out.

You must work in very different circumstances from mine. In many cases I'm lucky if I can plumb a prism pole on a corner monument due to fences, walls, trees or other obstructions. Setting up an instrument on one is a rare luxury. In any case, there's nothing wrong or irresponsible or mathematically deficient in side-tying corner monuments, as long as your field procedures are up to snuff.

The only surveyors who need to occupy corner monuments are those who don't know how to tie them into a network by other means.

[TTaylor]

As a tangent to this subject, In 2001 when I was writing the Caltrans RTK Specifications I was traveling to the NCGPSUG meeting with a couple of NGS folks and in the course of the conversation I asked the question, “If I have a 5 second instrument can I get a resultant angle with an error less than 5 second?”

One of them answered that it can’t be done. Of course I replied that yes it can and was met with an angry tirade that ended the discussion.

If the discussion had continued I would have pointed to the 1984 FGDC Standards and Specifications for Geodetic and Control Networks and the reliance on the standard error of the mean to achieve the reported precisional order.

Anyway, with the advent of GPS in 1989 the FGDC “Geospatial Positioning Accuracy Standards Part 2: Standards for Geodetic Networks” which shifted the reporting standards to network and Local accuracies (positional tolerances) which emphasized the reporting standard but was weak on specifications.

This is where the idea was being put forward that licensed surveys could make those decisions for field procedures.

I argued that in that case one person’s 2cm is not as good as another person’s reported 2cm when one was diligent and the other took a one epic reading and called it good. This “levels the playing field” for geodetic and control surveys.

In instances where a particular spec can’t be met, that is a decision made by the pro and should be elucidated in a note as to why.

That having been said, IMO there are a lot more moving parts in boundary related surveys, which makes it more difficult to come up with a one-size-fits-all set of procedures.

I will repeat that I think the “meter” used in the original survey that initially established the boundary being retraced should be the measurement standard that subsequent surveys adhere. In other words, if that survey measured 100’ at the time that is now 99’ as measured today means today’s equipment is off by 1’ compared to the initial survey.

2 cents

[SPMPLS]

"One of them answered that it can’t be done. Of course I replied that yes it can and was met with an angry tirade that ended the discussion."

Initials of M.I. by chance?

[TTaylor]

SPMPLS

No

[PLS7393]

You must work in very different circumstances from mine. In many cases I'm lucky if I can plumb a prism pole on a corner monument due to fences, walls, trees or other obstructions. Setting up an instrument on one is a rare luxury. In any case, there's nothing wrong or irresponsible or mathematically deficient in side-tying corner monuments, as long as your field procedures are up to snuff..

Jim, I'm not talking about corner monuments, as I read the statement about side tying control monuments. Hope that clarifies my view point.