Accuracy standards - how would we define them?

[CBarrett]

Let's have a conversation about accuracy standards in surveying - if we were to add a section about accuracy standards in surveying to PRC code...
What would it contain?

Definitions of surveying task that fall under accuracy standard requirements (what would those be?)
required Accuracy ranges for those tasks:

How to address when accuracy was deviated from.

I am not looking to force everyone to work within certain accuracy ranges, but bein able to document in somewhat simple terms what accuracy the survey fell under. This would include High precision work, and low precision work - including GIS cartographic work.

Once we have these defined, we can much easier fight the battle of what work needs to be performed under an LS, because it needs to fall under a certain accuracy standard, or have an exemption document stamped by an LS... or something along those lines.

[Mike Mueller]

Like with the 8771 debate, a clearly stated problem to fix, or goal to accomplish would help as I personally don't see this a survey quality problem.
My take is that it is a branding/market differentiation issue.

Survey quality is measured by reporting the correct measurements between the right monuments. I think we can agree that ensuring the right pipe is shot is beyond the scope of an accuracy statement. That leaves better measurements. The gear being used these days removed much of the physical skill needed to make a good measurement, as well as the need for much of the redundancy. When we had 10 second guns, doubling shots for control was a no brainer, now the guns are all 1 second. 1 second of angular error is only 0.000485 off at 100'. (tan(1/60*60) x 100') The day that is a problem we need to address is going to be a wonderful day :) Aiming at the prism correctly was a skill, now its automated. Plumbing a rod required at least attention to detail, now the GPS rod takes the "right" shot regardless of how caterwampuss I am. If my measurements are being taken more accurately and precisely than they were even 20 years ago, what is the new harm being solved with accuracy statements?

Since this is just a market differentiation issue, what products are we trying to differentiate? Is this meant to be utilized by surveyors to try and show how other surveyors are less accurate in a court case? IE differentiate good vs bad surveyors. Or is it meant for wider consumption like getting planners and permitting agencies to differentiate the work of surveyors vs non surveyors?

If it is just for surveyors, my experience with most offices is that they have their "gps person" or "math person" who actually understands gps/adjustments/statistics (hopefully) and the rest of the office just follows their lead, so how will an accuracy statement do anything more than the network report on a static control network?

So clearly this is intended for a wider audience and is trying to seperate surveyor's work from others. Which means it needs to be wildly simple, and if successful, iterate and update.

One thought for implementing it within the PRC would be to tie it to setbacks so that a setback dimensioned on a plan or map could only show significant figures less than the boundary it is being setback from. The inspector wants a 5.0 setback, then that boundary needs to be dimensioned to the hundredth. That way I could still show a house 300' away from a boundary satisfies the 20' front setback on a GIS siteplan, as long as I did a range. It would also tie accuracy/precision to something concrete and re-measurable like a building, which can be used to test the assertion made on maps, as well as tied to something that is understandable to everyone, not just a competent surveyor. Don't get me wrong. I know adding a hundredth to a dimension style accomplishes nothing in actually getting better surveys, however it might be a step we could all agree to in getting the lowest performers at least showing how wrong they are, or planners to look at a map closer?

Or the accuracy grade chart from that other thread.

Mikey Mueller, PLS 9076
Sonoma County

PS This discussion will immediately get accuracy and precision conflated/switched or equivalated, and even if all those posting here are aware of the differences, that will almost certainly not be true when this is brought to a statewide audience. It might be worth just accepting that and building it into whatever standard is proposed.

[David Kendall]

Class 1 - Urban 1:100,000
Class 2 - Suburban 1:50,000
Class 3 - Rural 1:20,000
Class 4 - no one cares 1:5000

Client can choose which one they want

[hellsangle]

It's the "Expert Measurer" debate again.

If the writings call for a monument then 2077 of the Civil Code of Procedure states the monument is the point. No matter what precision you have measured to get to that point. The point is the point. Period.

A survey might have a beautiful least square ellipsis . . . However, basis on the rantings of some, (that there are only half-dozen surveyors in the State that are capable of surveying) - more often than not the "precision" surveyor may miss the true corner but give an appearance of an infallible position, (because of their mathematical masturbation). What's the point?

"Expert-Measurer" courses will then be expected to be shown to seconds and thousandths(?) . . .when the original subdivision was to the nearest minute and nearest foot or tenth! See how we can get caught up in math and start thinking like an engineer?

Once we go down the "precision" road . . . surveys will cost much much more . . . and the surveyors that follow your new law will be sitting on their hands while the ones that don't file, don't set their tags, etc. will be busier than the rest of us.

I agree with Kendall one in "x" parts.

Why don't we throw in a Three-Signs law while we're at it and soon nobody will belong to CLSA!

More laws = less freedoms.

Crazy Phil's two cents

[CBarrett]

It's the "Expert Measurer" debate again.

If the writings call for a monument then 2077 of the Civil Code of Procedure states the monument is the point. No matter what precision you have measured to get to that point. The point is the point. Period.

A survey might have a beautiful least square ellipsis . . . However, basis on the rantings of some, (that there are only half-dozen surveyors in the State that are capable of surveying) - more often than not the "precision" surveyor may miss the true corner but give an appearance of an infallible position, (because of their mathematical masturbation). What's the point?

"Expert-Measurer" courses will then be expected to be shown to seconds and thousandths(?) . . .when the original subdivision was to the nearest minute and nearest foot or tenth! See how we can get caught up in math and start thinking like an engineer?

Once we go down the "precision" road . . . surveys will cost much much more . . . and the surveyors that follow your new law will be sitting on their hands while the ones that don't file, don't set their tags, etc. will be busier than the rest of us.

I agree with Kendall one in "x" parts.

Why don't we throw in a Three-Signs law while we're at it and soon nobody will belong to CLSA!

More laws = less freedoms.

Crazy Phil's two cents

There's a lot more to surveying than just boundaries. You can continue to do boundaries the way you already have, and not bat an eye. The plan is to not affect it.

This is the groundwork needed in order to stop erosion of market segments, other than just boundary surveys.

We need these classifications to solidify our position in other aspects of surveying and cartography and photogrammetry applications. Digital twins, underground utilities, GIS applications, topographic data collection all need accuracy classification guidelines. Being that surveyors are the only discipline which can quantify accuracy, then one can require accuracy certification for, for example underground utilities.

If you are doing boundaries, you can do business as usual, and let other set the groundwork for the rest of surveying applications.

More laws, you're in california, get used to more laws. Want to do boundaries only, and not be bothered with other surveying market segments, I hear you can move to Texas. They have that already.

The rest if us would like to develop business models that do more than $2000 ma and pop boundaries at rock bottom prices.

Noone said a thing about RS filings with respect to accuracy standards. You are reacting to a different debate.

If you are a surveyor, and cant see the point of accuracy standards, where the hell did you learn to survey anyway? I dont know how to begin to answer that without coming across as.... I dont even know where to begin. You asked what is the point? Are you even a surveyor? I take it you don't close your traverses and dont check your measurements. It's all just... freeform?

[CBarrett]

Class 1 - Urban 1:100,000
Class 2 - Suburban 1:50,000
Class 3 - Rural 1:20,000
Class 4 - no one cares 1:5000

Client can choose which one they want

I'm thinking about surveying other than boundaries.
Scanning, digital twins, engineering design topos, architectural facade scanning, GIS data collection for a variety of purposes, underground utilities...

This wouldnt be a requirement, but a toll which can be used to have unified classification of standards, should they be required on a project.

For example, we did a monument preservation project, where a city surveyor had a hard tome u understanding precision and resulting accuracy on centerline ties. One minute two tenths were ok, the next 0.01 caused consternation. Lack of specs, by more than one party to the contract and work. I am glad I didnt work on that one.

Another point, 1:10,000 etc only works if you are running traverses and compass ruling them. If you are doing GPS and least squares, you have to define horizontal and vertical 95% confidence level ellipses.

GIS work for example, for certain work, 2 foot error ellipse may be acceptable. How can you show this on your map? Hire a surveyor to be a part of the project and data analysis.

How do you get APWA people to not issue permits on crappy site plans? Require certain accuracy levels for certain permits.

You need a permit for something in the middle of a 10 acre property. Maybe accuracy "z" GIS line at plus or minus 10 feet are close enough.

If you are splitting a 10,000 SF lot by SB9, and everything us up against the setback lines, you may need a class 'B' boudary survey, so you know things down to a tenth.

Who can offer these classification declarations, when needed... a surveyor, who has the capacity to understand when different precision is needed, and ability to quantify them, and resulting accuracy levels.

[CBarrett]

Mike, I like what you are saying, I need to re read it after dinner.

[CBarrett]

anyone want to make a list of different types of surveys?

[CBarrett]

Snipped for brevity

You are correct, I am looking to have different levels of precision, and resulting accuracy defined, for a wide variety of surveys.

This is not intended to force anyone to operate within certain parameters, but to have some definitions put in place so that they can be used, and referred to if or when needed.

Site plans that you pointed out are a perfect example. It would give us tools to communicate with agencies in simpler terms.
It would give is more universal tools to quantify what we did, when the need arises.
It will also give us tools to define what kind of work they are applicable to, thus outlining what kind of work needs LS oversight.
Need your machine control to be +/- 0.2 for rough grade? Hire a surveyor to be sufficiently involved to sign off on it.
Need a pad cert for inspection... well we already do that.
Need to quantify accuracy of underground survey... only surveyors have the skill to run the data through rigorous statistical analysis and check the datums.
Same for GIS.
Same for site plan topos, design topos, (alta topos are already defined)
Teach the agencies what classification are needed for what kind of permits. Give them a codified list they can reference in their local ordinances, if needed.

Codify that only licensed surveyors have the expertise to place accuracy statements on a variety of our product.
If it benefits us to ever require, by law, accuracy statements on certain products, we have a useful mechanism in place already.

Need to classify something on a contract or during QBS process, or in project requirements?
Need to differentiate your product from "my site plan" junk in terms a lay person can understand?
How about, $4000 and you are getting a class "A" survey. $200 and you are getting class F. Here's is the difference in where you can use them.

Use class F in a boundary dispute, your chances of winning are not very good. Class 'A', better chance, that's why it costs more.

We need simpler terms to deal with all of this, and not lose people with technical minutia they don't understand.

Hey planners, you want a record data map because it costs less. Cool, accuracy classification level: "unknown", or can not be quantified. Need to have higher confidence level in the data, this is what class "...." will take. What does your client need for this project phase? Well the local ordinance says minimum Class "C" for the (I dont know, environmental assesment of some sort).

Hey engineers, you insist record boundary is sufficient for minor right of way takes? Want to use AP maps for ROW's? Sure, it gets "unknown" accuracy rating. Want to know what that means, sure it is described in the PRC. Show the 'unknown' to the client and see if they, or their risk management people are comfortable with that product.

As I'm thinking about this out loud, it would almost have the function of optional ALTA items.

Need agencies to pull back on allowing large design build construction companies work without properly done surveying, against licensure. Have them throw accuracy classifications in the contract. Oh, hey, look, you need a licensee for this to oversee the process...

[bryanmundia]

I am kind of fond of the Cal-Trans Accuracy Standards.

https://dot.ca.gov/-/media/dot-media/pr ... s-a11y.pdf

[CBarrett]

I am kind of fond of the Cal-Trans Accuracy Standards.

https://dot.ca.gov/-/media/dot-media/pr ... s-a11y.pdf

Nod Nod, excellent idea! I was revisiting those just few weeks ago. It might be a good starting point. I need to find time to dig a bit deeper, I'm not sure when that will happen.