Doing an A.L.T.A. requires Least Squares?

[yoram]

Hello all,

I wanted to know since an A.L.T.A. requires relative positional error between two points (monuments) of 0.07' + 50 PPM, is a least squares adjustment the only way to obtain such results? In other words if you perform an A.L.T.A. without using least squares, have you violated what you are certifying to?

It seems to me many are still performing A.L.T.A. Surveys using closure ratios or compass rule adjustments. I believe in order to validate this requirement other then the certification itself is to list the relative error of each line? Maybe an overkill, but just a check that others are on the same page.


Thanks,

Teddy

LS 8583

[dmi]

How do you propose to state that you have met the standard? When you sign the certificate, you are stating thAT YOU HAVE MET THE STANDARDS.

[yoram]

To me it seems that the measurement component of Surveying has always been a hidden undelay until one has physically measured the points in the field. I have come across too many A.L.T.A. Surveys that don't stand up to this requirement or standard. Perhaps is why so many record boundaries exist?

Teddy

LS 8583

[pls7809]

I don't believe that you have to report relative error of each line on the map, but you do have to meet the requirement and have back up for that in case you are sued or brought before the board or...

[pls5528]

The article written by Gary Kent (although it speaks of the change over from the ALTA standards in 2005) puts some clarity on this subject.

http://www.amerisurv.com/PDF/TheAmerica ... ug2006.pdf

I hope this helps?

Mike

[LS 4722]

In other words if you perform an A.L.T.A. without using least squares, have you violated what you are certifying to?

No. LS is just one way to test for RPA, careful procedure and common sense is another way. The 95% confidence level is what you want to achieve for RPA, how you do it is NOT confined to LS.

[Jim Frame]

I believe in order to validate this requirement other then the certification itself is to list the relative error of each line?

The relative positional precision specification pertains to the relationship between any two corners of the surveyed property. In order to tabulate the RPP of each line, each corner would have to be numbered or otherwise designated, and the RPP between each conceivable pairing listed. For parcels with a lot of angle points, that would result in a big table that wouldn't impart much useful information.

I agree with those who say that you have to be prepared to back up the certification with statistical documentation, but don't have to put the numbers on the map. As a practical matter, though, I don't see how anyone can satisfy the RPP spec without running a least squares adjustment of their measurement data, except on the simplest of surveys.

[yoram]

Jim,

Thank you, I agree it doesn't make sense to try and use an older system (Compass Rule) that in reality cannot isolate an error ellipse at one position other than computing manually, let alone with the effects of computing relative relationships or RPP of an entire site. I also agree for many of the sites we do, there hasn't been a project that doesn't come with traversing challenges (short back sites, can't occupy on found monuments and long traverse propagation that GPS must resolve unless local control is within site). Therefore I ask, is it possible to do an A.L.T.A. (other than simple basic sites) without the use of least squares and without spending ridiculous amount of time to determine your RPP without the aid of least squares. Also thank you Ryan, I also agree that if challenged you better be ready to have courts or the board understand your procedures for developing RPP without the aid of least squares. Like Mr. Gary Kent mentions even though it does not specifically say a least squares must be used, it is the only tool that can test your measurements in order to make sure you are achieving the standard of (0.07' + 50ppm) to every connection.

We all know measurement is only one component of completing a sound survey, but now that you've spent all day digging and finding the senior monuments that control your property, can you measure those monuments and quantify your RPP between them?

Thank you for responses, it makes me feel better that I'm performing as I should.

Teddy

LS 8583

[dmi]

If you are not going to use LS, then what method or process do you proposed to use to meet the ALTA standard?

Can someone explain how being careful would provide the data necessary to prove the standard was met?

I ask because I hope to learn something new.

Thanks for your help

[Jim Frame]

Can someone explain how being careful would provide the data necessary to prove the standard was met?

The ALTA specification doesn't say you have to prove that you've met the standard, it only says you have to certify that you've met it. While I don't endorse the procedure, I can see where a practitioner who is familiar with his equipment and methods can feel confident that he *would* be able to demonstrate compliance if required to do so. I think that's what Paul was alluding to.

Pretty much every job I do -- even a 4-legged closed traverse -- gets run through Star*Net as standard procedure, so it's not an issue I have to worry about.

[LS 4722]

Is quite a bit of slop. The ALTA surveys I do in my area are usually rectangles less than an acre in size.

[dmi]

Either the surveyor has met the standard or they have not met the standard. It is either true or false that a surveyor who signs the ALTA certification has met the standard. My question is HOW is the surveyor ,signing the ALTA certification, going to assure themselves that they are making a true statement when they sign the certification,stating that they have met the ALTA standard?

OH, well I was very careful, so I know I met the positional tolerance standard.

For most urban surveys with good control, it is fairly east to meet the standard of 0.07' plus 50 ppm. Surveyors with plenty of experience know this anecdotally, as Paul mentioned in his post.

[yoram]

Dmi,


Generally speaking for myself, when I bid on a 0.15 or 30 acre site (or however large or small) I don't use the sense that good control will be available to me or that the property is configured to manage an "Experienced" decision. Rather an experienced mind set would be to take in typical surveying factors that are encountered when performing surveys, such as, line of site, short turns, strength of figure, monuments that cant be occupied, or traverses that cant be closed. So personally I don't let the project dictate whether I can or cannot meet the standard, I use least squares on all my projects to let me know whether I met the standard.

So how do I assure myself when I sign an A.L.T.A., I generate a least squares report (on all my surveys) that will tell me that all my controlling monuments shot have met the RPP standard, I then feel rest assured that I have data that illustrates quantifying my measurements. To me surveying projects already have more than enough land minds, so I'd rather concentrate on the more critical issues on a survey rather then worry if my site is configured easily or has sufficient control to meet a measurement standard.

My respect to all surveyors young, old, experienced and those trying to gain experience. I only posted this thread because I know as an "Experienced" surveyor, no site is an "Easy" site. Perhaps when California mandates measurement standards this post may become more relevant?

Teddy Ohana

LS 8583

[LS 4722]

Perhaps when California mandates measurement standards this post may become more relevant?

Hah! That'll be the day. California doesn't even have monument standards.

[LS 4722]

My question is HOW is the surveyor ,signing the ALTA certification, going to assure themselves that they are making a true statement when they sign the certification, stating that they have met the ALTA standard?

That's a pretty simple question to answer.

1. Run your control, check in.

2. Calc your boundary.

3. Do the work, set your calc corners. Take a new shot on sets.

4. Load the new set corner numbers on top of the calc corners.

5. Compare tic marks.

Sheesh. If I ever find a set of tics more than 0.07' (+ 50PPM) apart that gets reset and reshot cause I know I shot using reflector less instead of prism. Most sets vary from a 1/16 " to a tad over an 1/8".

[land butcher]

It never ceases to amaze me how a governing body can put language in a a law that Is so blatantly monopolistic.
0.07 + 50ppm should be achievable with most everything inc a rag tape.

[yoram]

So in receiving the responses above, I’m not sure if my question was answered? Those whom agreed that a least squares would be the most logical and perhaps the only way to prove your measurements, I thank you for the reinforcement to my daily work. Those whom feel they can certify to an A.L.T.A. Survey without the aid of a least squares or whom can satisfy the RPP tolerance of (0.07’+50ppm), then I would be grateful to see your measurement reporting these connections that would meet this standard without the use of least squares. I’m not asking for a procedure nor a statement that this is an easy standard to satisfy, I’m asking for some type of computational report that issues “Statistical results” of your measurements (+ or -) to each connection (or monuments used that established your property) that would conclude you have met the standard. With almost 6000 views perhaps I may get a response or answer to “My” original question.

National standard, Yes, but still a standard that must be adhered to in order to perform such survey.

When the board receives an issue with an A.L.T.A. Survey, (Establishment of lines or no RS Filed) do they review this standard? Or ask for such data? Don’t know and perhaps will never know (input Ric?) because of how I process my work.

Thank you,

Teddy Ohana

LS 8583

[RAM]

So on your least squares adjustment of your measurements, where is your redundancy? Do you have a main traverse loop with cross ties? Do you run a traverse and there re-tie all control with GPS? My least squares education was long ago and is now fuzzy.

[LS 4722]

When the board receives an issue with an A.L.T.A. Survey, (Establishment of lines or no RS Filed) do they review this standard? Or ask for such data? Don’t know and perhaps will never know (input Ric?) because of how I process my work.

Why would the board even care about an insurance company's standard? Ask for data?? Please!! Quit complicating this whole thing Teddy. When I started doing ALTA Surveys, it was a survey that showed anything within five feet of PL.. PERIOD! It's the attorneys (and some very bad surveyors) who prompted ALTA standards anyway. Standards are just that, they are not law.

[yoram]

Ram,

Thank you for asking, I was in anticipation of having to offer my procedures that would be defensible as well as acceptable to the standards of an A.L.T.A. Survey (2011). To simplify your questions, Yes on redundancy (always when not occupying a monument), a main traverse, always but at times a closure may not occur because of lay of property. Cross ties (whenever possible), definitely if needed to condition traverse network appropriately. So for the GPS aspects, the idea is to understand your network design and experience can only make this happen easier (not least squares). I personally use RTK for redundancy (at a few network nodes) should I feel I have no means of cross ties, redundancy, or local published control. The RTK or GPS acts as another source of redundancy to the traversed legs that are not so great (short turns, Heat wave, Traffic, long traverses creating error propagation, Etc.). So in all essence without the use of RTK or GPS, this should be a typical survey procedure for an everyday A.L.T.A. Survey keeping in mind your trying to achieve the “Standardâ€￾.

I was trying to gather perhaps another acceptable method (besides least squares) that would give me “Statisticalâ€￾ data for my measurements. Not really what I want, more so, what an A.L.T.A. Survey requires.

So again if you’re doing an A.L.T.A. Survey, without this type of procedure or access to least squares, I would highly recommend to rethink it before you sign that certification. Personally, I would not fear the challenge of courts or the board, rather I would fear how you would demonstration a procedure without your physical “Measurementsâ€￾ or statistical data backup. I have attached a pretty simple survey that has everything mentioned by “Ramâ€￾, without the use of RTK or GPS because it was not needed. Also I wanted to eliminate the registered monuments found for privacy. Lots of good “Real Dataâ€￾, Thank you Ram for inquiring and allowing me to demonstrate.

Teddy Ohana

LS 8583

[Tom Milo]

One quick note. Most ALTA surveys I propose on are always price sensitive first and time sensitive second, one reason I don't do a lot of them. If you want to make all the cross ties and checks and include that in the cost of the survey, I doubt you'll have to worry about positional tolerance, because you are priced out of the market and will not be doing the ALTA.

[yoram]

Why would the board even care about an insurance company's standard? Ask for data?? Please!!

When I started doing ALTA Surveys, it was a survey that showed anything within five feet of PL.. PERIOD! It's the attorneys (and some very bad surveyors) who prompted ALTA standards anyway Standards are just that, they are not law.

The Board should care about any surveyor who certifies that he or she conducted a survey in accordance with a standard, but, in fact, did not meet that standard. That sounds like fraud to me.

The ALTA/ACSM Standards original 1962 standards required a positional tolerance on urban surveys of 0.02 feet!

The ALTA/ACSM standards did not come about because of attorneys and bad surveyors; they came about because of the need for a common understanding of what title companies could expect from surveyors anywhere across the country when they need a survey because their clients requested extended coverage on their title policy.

Teddy

LS 8583

[LS 4722]

Sorry, I should have clarified this..

It's the attorneys (and some very bad surveyors) who prompted Kent and Company ALTA standards

So Teddy, don't you think that a jump from 0.02' to 0.07' + 50PPM is indicative of a lot of bad surveyors?

[yoram]

I'm not writing the standards, just obeying them. I've provided the logic and my good faith samples, I hope others understand measurement is not a push of a button.

My apologies LS4722.

Teddy

LS 8583

[Dave Karoly, PLS]

Wow, you have a lot to learn, young whippersnapper.

I would rather follow Paul on a Survey then some technocrat with a pocket stuffed full of Least Squares output reports.