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foxtrot_xray

'(in)complete Digital Data Sheets'

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Hey all, looking for comments..

 

I really WASN'T searching for benchmarks, and stumbled across one on the side of a building. I took pics, and went to go look up up based on where I was. I found it, but got an error sheet, of which the beginning reads:

-----------------------------------------------------------------------------
-   This listing contains control for which complete digital                -
-   data sheets where not provided.  The complete data sheets were          -
-   not provided for the reason listed below.  The reason below is          -
-   associated with a horizontal control Nonpub code shown under            -
-   the heading 'H' and/or a vertical control Nonpub code shown under       -
-   the heading 'v'                                                         -

 

I know it's the right one, as the stamp matches the name that was listed:

-----------------------------------------------------------------------------
 Pid    Name                           Lat        Lon         Elev     O o Hv
 ------ ------------------------------ ---------- ----------- -------- - - --
>AR0462 T 1                            29 39 05. /082 19 26.                D

 

..So, my question is, since we know where it is, should we inform NGS so they can update their records and GET a 'digital data sheet', or is there maybe REASONS why they don't have one. (I.e. Incorrect, etc..)

 

(Also... On the second line, ''where'' should be ''were''.. Just a grammar/spelling fix. :laughing:)

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Data Sheet Page

 

Then Click on: DATASHEETS;

PIDs;

Type :AR0462"

Check the box for "Include Destroyed Marks"

Click on "Submit"

Click on the line in the box to highlight it

Click on "Get Datasheets"

 

Gives me this:

 

 

 

The NGS Data Sheet

See file dsdata.txt for more information about the datasheet.

 

DATABASE = Sybase ,PROGRAM = datasheet, VERSION = 7.16

 

*** retrieval complete.

Elapsed Time = 00:00:00

Msg=FATAL_ERROR - No Marks found

 

-----------------------------------------------------------------------------

-  This listing contains control for which complete digital                -

-  data sheets where not provided.  The complete data sheets were          -

-  not provided for the reason listed below.  The reason below is          -

-  associated with a horizontal control Nonpub code shown under            -

-  the heading 'H' and/or a vertical control Nonpub code shown under      -

-  the heading 'v'                                                        -

-                                                                          -

-  The format of the records are as follows:                              -

-      Pid  = Station Permanent Identifier)                                -

-      Name = Station Designation                                          -

-      Lat  = Approx. Latitude (Degrees, Minutes, truncated Seconds)      -

-      Lon  = Approx. Longitude (Degrees, Minutes, truncated Seconds)      -

-      O    = Horizontal Order                                            -

-      o    = Vertical Order                                              -

-      H    = Horizontal Nonpub Code                                      -

-      v    = Vertical Nonpub Code                                        -

-                                                                          -

-      H Nonpub HORIZONTAL CONTROL NONPUB REASON                          -

-      -------- --------------------------------                          -

-      X        Surface Mark Reported Destroyed                            -

-      Y        Surface and underground mark reported destroyed            -

-      A        A-Order Horizontal mark not tied to an adjusted HARN      -

-      C        C-Nonoperational CORS Station                              -

-      W        Weakly determined position.                                -

-      P        Purpose of position is not for network control            -

-      D        No Descriptive Text available                              -

-      R        Restricted position                                        -

-      O        Outside NGS Publication Area                              -

-      N        No geodetic control at this mark                          -

-                                                                          -

-      v Nonpub VERTICAL CONTROL NONPUB REASON                            -

-      -------- ------------------------------                            -

-      X        Surface Mark Reported Destroyed                            -

-      Y        Surface and underground mark reported destroyed            -

-      F        Bench Mark not yet adjusted.                              -

-      D        No Descriptive Text available                              -

-      Z        Presumed destroyed                                        -

-      R        Restricted elevation                                      -

-      O        Outside NGS Publication Area                              -

-      N        No geodetic control at this mark                          -

-                                                                          -

-                                                                          -

-  NOTE - Stations found in this listing may still have a valid            -

-          datasheet produced by use of other publishable values.          -

-          For example, an ADJUSTED height may be non-publishable          -

-          but a good GPS height might be found on the datasheet.          -

-          This listing does not imply that values found on the datasheet  -

-          are restricted.  If it's on the datasheet, use it.              -

-                                                                          -

-----------------------------------------------------------------------------

  Pid    Name                          Lat        Lon        Elev    O o      Hv

  ------ ------------------------------ ---------- ----------- -------- - - --

>AR0462 T 1                            29 39 05. /082 19 26.                D

>AR0462 T 1                            29 39 05. /082 19 26.              NN

 

 

When I read the whole page, I see that the "v = Vertical Nonpub Code" "D" means no descriptive text available. The N under both the Vertical and Horizontal NonPub Code means "No geodetic control at this mark."

 

So the mark is of no use for geodetic purposes. Hence, no reason to produce a data sheet with an updated description.

 

GH

Edited by GH55

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Foxtrot,

 

Sorry, that station is destroyed.

 

When you see that, they destroyed it and could have for any number of reasons.

 

Good Luck!

 

Rob

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foxtrot_xray -

 

I've run across this before also. The PID is not destroyed and not in the 'Destroyed' category. I don't know what 'no descriptive data' means. Obviously there's no To-Reach description, but why not put the adjustment data, etc.?

 

If you do a Radial Search on your PID's coordinates and put in a radius of 1 mile, you will see several marks that are listed at the end of the report with no datasheets; three of which are coded Destroyed, and six, including yours, are not coded as destroyed. Instead, as you noted, they are coded

D No Descriptive Text available.

 

It would be educational for us all if you did submit a mark recovery on this mark, since the position and designation match. I imagine that Deb will let you know what the deal is. Then, you can tell us. :laughing:

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It would be educational for us all if you did submit a mark recovery on this mark, since the position and designation match. I imagine that Deb will let you know what the deal is. Then, you can tell us.

 

Frankly, why submit a recovery when there is "No Geodetic Control at this Station?" Submitting a recovery report is supposed to be to help NGS in its mission.

 

For some reason, there is a marker that is not useful for geodetic purposes. Since it is not useful, there is no reason to publish a datasheet. Hence, submitting a recovery will not help NGS. It will only increase their workload.

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BDT,

 

I can help with what no descriptive data means. If you look, they do not designate this station as either vertical or hoizontal control, what they do tell us is that there is nothing they can tell us. They have no data to describe the station.

 

I have destroyed a lot of stations in my career, and surveyed from a few too. When I pull a page like this, it means to me that the NGS has decided to pull control. They can state a number of reasons, but it still isn't going to give me survey control. Some I have destroyed will say different reasons for being pulled, but when you see this page, the PID is not considered active any more.

 

This code means there is no Data here. Data is the be all end all of being able to survey. when there is no data, well, we surveyors don't go there. Unless we will be establishing said data and in this case that had already happened.

 

I can surmise from what I know about station naming conventions that this was once vertical control. But without data, there is no control. I could have a brass disc in the ground but without data, I cannot use it. It is effectually, destroyed. You could take me to task on semantics all day if you like and I'd be ok with that, but it is so rare when this sort of thing happens that they ever come back. This could be a station that could come back, but that would be an exception to the rule. I would say for most intents and purposes, this one is gone.

 

Thanks,

 

Rob

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I can surmise from what I know about station naming conventions that this was once vertical control. But without data, there is no control. I could have a brass disc in the ground but without data, I cannot use it. It is effectually, destroyed.

 

This was one of the most difficult things for me to grasp when I first entered the hobby. If I found it, how can it be destroyed???

 

May I recite the classic example of the disk mounted in the brick wall of the train station in Statesville, North Carolina? A few years ago, the train station was moved from north of the tracks to a new location south of the tracks, where it became a visitors center.

 

The disk survived the move. I've seen it. However, not only is it hundreds of feet away from the original location, but the "up close" description is not valid. (When the building was set onto the new foundation, it was rotated 180 degrees. Now, instead of being WEST of the waiting room door, the disk is EAST of the door.)

 

Test Question: When reporting this find, what category best describes the mark? Your choices are:

 

GOOD? The disk is in excellent condition, is mounted firmly in the wall, and is easy to read.

 

DISTURBED? It is typical to use this description for a disk which is leaning, or which otherwise might produce an error if used.

 

DESTROYED? Although the disk is mounted securely to the wall and is easy to read, all attributes of the station have changed. This disk should not be used for any purpose related to surveying, and remains only as a curiousity in the side of this historic building.

 

-Paul-

 

P.S. Actually, there is a fourth choice. One can submit a NOTE. This can be done directly on the recovery record at GEOCACHING.COM. With NGS, it must be submitted to the staff, who then can enter a SEE DESCRIPTION notice in the History. And, of course, there is the universial fifth choice: Do Nothing.

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This could be a station that could come back, but that would be an exception to the rule. I would say for most intents and purposes, this one is gone

 

Well stated, Rob! (You have a great way with words!) Last week, I was at the NCGS office in Raleigh, looking over the shoulder of Roger Barns as he pulled up computer images of very old stations he has found--some dating to the year 1813.

 

I asked him when we could expect to see these show up in the state or national data base. "Never," he replied. "Although they are of historical interest, they have no value as points to be used for surveying."

 

Roger went on to explain the same thing that the professionals in this forum have been saying, all along. To merit being in the data base, a mark must meet a high standard of accuracy.

 

-Paul-

 

-----------------------------------------------------------

On the porch of the NCGS office building, there is a

bronze disk marked ELKS. (They are in the old Elks

Building). The disk is stamped 1909, but it is not in

the data base. Say, isn't this like the headquarters

of Otis Elevators being in a one-story building?

------------------------------------------------------------

Edited by PFF

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I would add this. Many old USGS marks fall into this same catagory. USGS says the methods employed when the marks were set is obsolete and no futher ties are warranted.

 

Many of the marks were thought to be set to 3rd order standards, by todays standards they don't come close.

 

usgs-20.jpg

usgs-10.jpg

Edited by Z15

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This is interesting.

 

Lots of survey marks don't get into the NGS database because insufficient rigor in calculations was done, or the proper form was never forwarded to the NGS, or whatever. Yet, these stations, with the "D" code and a PID, did make it into the database.

 

evenfall Posted on Apr 21 2005, 03:58 AM

When I pull a page like this, it means to me that the NGS has decided to pull control.

This must be the case.

 

It would seem that the NGS doesn't want to call the station destroyed, probably because it is someone else's station who may still have a use for it, and the NGS has no information that the station is actually destroyed. (From foxtrot_xray's report, the station still exists.) But, for whatever reason the NGS has decided that the station's data is not useful for them? Perhaps the adjustment procedure indicated that the station has bad data? I would think that being adjusted is part of getting a station into the database in the first place, though. I find this rather interesting and I'd like to find out why the "D" code is used; what it means.

 

evenfall Posted on Apr 21 2005, 03:58 AM

You could take me to task on semantics all day if you like and I'd be ok with that,

Instead of that, I'd like to hear the answer from the NGS, as it is their database and their coding. :rolleyes:

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Okay, maybe *I* need to step back a minute. Thanks to everyone who replied, too - learning alot..

 

So, despite the fact it says "No Descriptive Text Available", it's NOT really referring to the ''directions'' (Turn left at 1st street, then look up as a bird flies over, and the control point will be on your left.), they're referring to CONTROL information?

 

(I mean, if it IS just the ''Directions'', hell, I can MAKE directions, I've been there, measured it and all.)

 

I also now see the "NN" codes, almost like it's a different entry for the same PID, referring to ''No geodetic control at this mark''. Can someone explain that? Not 100% sure.. (I mean, there's a disk there, so we have a point of reference..)

 

So, I guess my confusion is just over the phrase "No Descriptive Text Available". To me, that sounds like the directions just don't exist. However, compare that to DF2676.. Talk about no text. (That's one I plan on at least submitting directions to next time I'm down there..)

 

Thanks, everyone.

Fox.

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Foxtrot,

 

NGS won't publish a point if it doesn't have a location, elevation, and descriptive text.

 

They are not publishing anything we can use.

 

"If it's on the datasheet, use it". That is what they say, but there is no data to use.

 

To us surveyor types it is not usable. I think of it as destroyed. Many Surveyors would. We do not have the on the clock time to do other, unless this were the job, fix this station. Get Paid make a Buck. Z-15 has mentioned several times in the past as well, many projects lose funding and just pass away. They could be 98% done too. Oh well. It happens. Money makes it all go round and the bean counters are sure nothing is free.

 

If you want, you could contact NGS and offer a description, you know, descriptive text. If they have the rest of the requisite data, perhaps they will put it back. If nobody ever does anything, this station will never be published again. Since there is nothing usable on this datasheet, it is effectively same as destroyed to the potential end user. At least, until it is not.

 

BDT. No Matter. Until this station has met a requirement; They are calling for descriptive text, there is no data available which will be published to the public. NGS Policy. This is obvious as it is. It is not meeting criteria for no descriptive text. That is what the D code means. They do say feel free to use what is published but this time, nothing is. So to you and I, as readers of the datasheet, is is effectively destroyed. Not officially, just effectively. If you want to offer to fix the stations problem, I am sure they will publish it. For now, there is nothing here a surveyor can use. When I said Consider it destroyed, I do. NGS may tell you how to fix it and that is the Semantical part. Until it is fixed, it is unusable. Unusable is like destroyed to me. But if you can fix it, feel free.

 

Good luck,

 

Rob

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I understand that well-done property surveys sometimes start at a geodetic marker, so that if the markers at the property corners become disturbed, there is an additonal method to restore them. If a mark that used to have descriptive data were so used, it might be useful to a surveyor who is about to resurvey the property to distinguish between "destroyed" vs. "no information available".

 

I'm not a land surveyor, just a property owner, so I'm just guessing.

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Gerry,

 

The case with NGS is that they are a Government Agency and they are keepers of High accuracy Data. They make their own rules about that data. They are pretty tough on things actually. Tough on us too. But there is nothing wrong with high expectations.

 

They Have a set of rules in their agency that covers various reasons for not publishing Data. This means they may have a PID and Data, But not all the Data or whatever else that meets their criteria. So they don't publish. This PID has no descriptive text. I do not know why it does not but it doesn't. Now the NGS in their files may know everything else. the Stations order of accuracy, the various heights, Superseded info, everything. But their own rule is that they have no Descriptive Txt in this case, and there are other criteria but this is the case here. Since they do not, than they will not publish the PID.

 

We are free to use anything published on the datasheet, This PID is currently giving us nothing we can use, they would likely put this station back in service if they had descriptive text.

 

I see this happen more than you think. I'll pull a datasheet and this form comes up with various codes. In this particular instance, If no one ever furnishes descriptive Text for this station, it will never be published again, Not ever, Because most of us won't do it, as there is not Time to do it for what the bean counters says our time has to pay, and the NGS does not have field staff who can do it either. We all serve our Masters.

 

I know how to establish what the elevation is at this point, I know more way than one. I could even survey it to high horizontal accuracy. But, If I have no control for the point, I cannot certify the survey I am doing with this station. It has to come from published data and currently, there is no published data. NGS is not publishing the Data because there is not enough Data in their possession for them to meet their own criteria. So, to a Surveyor, this monument, and PID are valueless without Data. Even if I could reestablish it some way, NGS has to publish before I can use it to help certify a survey.

 

If someone gives NGS descriptive Test and NGS feels it is of adequate quality, they may put the station back into play, but until they do, to the end user, it is as good as destroyed, whether that is official or not. NGS will keep the data they have and never publish it, in perpetuity.

 

Rob

Edited by evenfall

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What stations are NOT published ???

 

The Latitude and Longitude is not published if one of

the conditions listed below exists:

 

    * Surface Mark Reported Destroyed

    * Surface and underground mark reported destroyed

    * A-Order Horizontal mark not tied to an adjusted HARN

    * C-Nonoperational CORS Station

    * Weakly determined position.

    * Purpose of position is not for network control

    * No Descriptive Text available

    * Restricted position

    * Outside NGS Publication Area

 

 

The Orthometric Height is not published if one of

the conditions listed below exists:

 

    * Surface Mark Reported Destroyed

    * Surface and underground mark reported destroyed

    * Bench Mark not yet adjusted.

    * No Descriptive Text available

    * Presumed destroyed

    * Restricted elevation

    * Outside NGS Publication Area

 

 

There a several old USLS stations in my area that are no longer published. They once (1962) were in old paper format ( I have that) but when the new datum was established in 1983 they found that these marks fell outside of the adjustment by too large a margin (several meters). The positions that were computed were thought back then (early 20th century) to be accurate but modern techniques (like GPS) has shown them to be obsolete. Nothing worse than bogus data.

 

Tell you a little story about a bench mark here at the airport. It was set in the base for a big dedication monument for the AP. Only problem is it was moved two times since it was set.

 

STATION RECOVERY (1996)

SG0012

SG0012'RECOVERY NOTE BY MICHIGAN DEPARTMENT OF TRANSPORTATION 1996 (BRT)

SG0012'--CAUTION--CAUTION--CAUTION--CAUTION THE CONCRETE BASE AND THE

SG0012'MEMORIAL PLAQUE HAVE BEEN RELOCATED TO THE NEW AIRPORT TERMINAL

SG0012'BUILDING (DEDICATED IN 1970) . THE EXACT DATE THIS WAS DONE IS UNKNOW

SG0012'BUT IN ALL PROBALBILITY AFTER THE 1975 RECOVERY. THE DISK CANNOT BE

SG0012'REMOVED FROM THE PLAQUE BASE WITHOUT THE POSSIBILITY OF DOING

SG0012'EXTENSIVE DAMAGE TO THE MONUMENT. NOT SUITABLE FOR SATELITE

SG0012'OBSERVATIONS DUE TO THE NATURE OF THE SETTING.

SG0012

SG0012 STATION RECOVERY (2001)

SG0012

SG0012'RECOVERY NOTE BY MICHIGAN DEPARTMENT OF TRANSPORTATION 2001 (MPR)

SG0012'THE AIRPORT MEMORIAL PLAQUE HAS BEEN RELOCATED AGAIN, IN 2000. NEW

SG0012'BASE, NO SURVEY DISK. CONSIDER THIS MARK DESTROYED.

Edited by Z15

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evenfall:

 

My point was that if a marker still exists, and has been used in some local property surveys, then a surveyor could try to locate the mark from the informaton in the property survey, and then use it to reestablish disturbed property monuments. If a surveyor was thinking about doing this, his/her decision might be different depending on whether the mark was listed as "no data available" or "destroyed".

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evenfall:

 

My point was that if a marker still exists, and has been used in some local property surveys, then a surveyor could try to locate the mark from the informaton in the property survey, and then use it to reestablish disturbed property monuments. If a surveyor was thinking about doing this, his/her decision might be different depending on whether the mark was listed as "no data available" or "destroyed".

That assumption is flawed. Setting a lost survey mark is more invovled then people think. A surveyor has to work within the laws of his state and the ethics of his profession.

 

A local property survey is not likely to be tied to a bench mark. Most all property is locally controled in a plat or meets and bounds description. State plane coordintaes or Lat and long at typical not a requirement for a property survey and would only increase the cost to the customer. Its rare to find a property survey tied to a bench mark of other control station.

 

A one more thing, no surveyor worth his salt is going to base his work on one control point, he would need a minimun of 2 to confirm the position and maybe more if there are descrepencies.

 

For instance, if you were to hire a surveyor for some land you have. Chances are slim he would use any of the NGS control points. If you insisted, it could double his work load and also you cost. And it would still not have any meaning to your property location. This is very complex topic that involves a lot of research and field and states require you to have a 4 yr degree to be a surveyor.

 

Also, on the subject of re-establishing sruvey marks on the NGS DB This is not a easy task to do. A elevation mark can be even a days work. A mark with lat and lon can never be put back in the same exact location as it was. Whats more what seems to you to be just one mark is actually part of a vast survey of marks all tied together and adjusted togeather. To take one out of the lot and reset it and say its the same mark is not correct. It been said that with the advent of GPS is much faster and cheaper to just set a new mark when and if you ever need it than to spend the time and money to reset an old mark. The ones you find in the NGS db were often reset as part of a survey and not just his one mark. Ones that were lone reset will always have a warning attached to it, something like "CAUTION-COMPUTED FROM UNVERIFIED RESET DATA". I have seen some guys dig a hole 2 ft deep, place a new survey disk in there, run some half-a** bogus levels with a construction laser level and say they reset the mark. How can anyone be expected to accept a mark like that when the way it was established it full of possible flaws.

 

I really got of on a tangent............

 

BMreset1.jpg

BMreset2.jpg

Edited by Z15

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The "Hints on description writing" are helpful. That would be an asset in the FAQ, in my humble opinion. I had surmised that compass directions, for instance, were to the nearest half quadrant simply because I had seen nothing to the quarter quadrant in an NGS description. Now I know that is the policy, or at least their suggestion.

 

The part about description being written so as to enable a stranger unfamiliar with the territory to find and identify the mark with ease is one of my criteria for making a recovery report. If the surroundings have changed so that finding the mark from the description is difficult without local historical knowledge, then I will submit a recovery with an updated description, even if the previous recovery was not long ago.

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Gerry,

 

Z-15, Mike gave you a very well rounded explanation. The NGS Datasheet is the only sheet of paper in the Nation I can use to certify the elevation or location, Mark type not withstanding, at that particular station. Nobody else is going to take responsibility for an NGS station.

 

My job is to survey it, and check what I get against it. If the two concur, then I am properly calibrated. That is what tells everyone else my survey is on the money. I may have to tie in to various points of known location or elevation to show I stayed on the money as I went.

 

How do I know that one station is not off? Well, To begin, I don't. I may have to include a couple of Stations of a similar type and quality, and see if the data compares favorably with what I got in order to be sure. I can tell you when you find any survey marker that does not agree with it's own data, you now get to be the lucky guy or gal who has to chase down why, because we have to find which one is making the survey not close, or if it was just an error we made ourselves. In other words, you are not done until either the survey closes, or you figure out why it wont by removing the specific problem from the equation, once you determine what it is.

 

The funny thing is that the methods for doing this and what you have to establish in order to do it vary, when based on the equipment you have.

 

I once found a bust when I was surveying on a platt, I was surveying for the installation of storm drain. Everything was fine until I had to stake the grade elevation to a storm tie in across the street on a different platt. The GIS Data that the engineer used on our side of the street was taken from one city, and the GIS data on the other side was another city. There was a 1.5 foot difference in published elevations, and this was not good. We took our survey across the street for the tie in and our numbers did not square. I had to trace back all my work, and include all the local control to see if my survey would close, meaning it was accurate. I went beyond that and checked further away from my control that was used for this platt to make sure it all jibed. It did.

 

So I was ok, but it didn't solve my problem. Storm sewers are gravity drained but they are kept pretty flat, and water won't run up hill.

 

Based on my info from my side of the street I went and got the Platt maps that had been filed for across the street and let the office know I had a problem, Got them to looking at some things. Control on the other side of the street was right, but at some point, either a TBM had been put in wrong or used wrong and a good bit of the storm sewer was as built, a bit more shallow than it was supposed to be. Maybe they caught it but somehow they made it work for them. They never filed the as built change and so this little problem was never recorded by the folks who did the work across the street. This means no one else would know the design change happened or how to design around it. The GIS assumes everyone has done their job. The next guy just comes along and plans with what it shows they can use. It is assumed to be an accurate representative of what is in place.

 

We now had to adjust some of our pipe runs and grade work in order to compensate for the error made by someone else across the street in order to get the storm water to flow in the pipe at 1-2 % grade. We like to have 2% but when this sort of thing happens, you may have to settle for less, and it depends what can be shuffled in the design. In any case, we have to get rid of the water as there is no pond designed for the location.

 

City control is using Geodetic control to help certify it's control. So is County, Borough, and State. It is a hierarchical thing. I look up their data and they say their city marker is NAD83 (1991) Or NAVD88 or what have you. That shows me that they certified their control from NGS survey and data. This is true much of the time, but States also establish geodetic quality control on their own and we use it too. So If I am at an NGS station and it had no control and it is the control for most other control in the area, and it could be, then we have lost control! Hehehe We're gunna crash! No, But we can't use it because there is nothing there to prove our survey is accurate. We have to use another Station. The Datasheet is the document we need. The other stations are likely fine. But this one, we cannot use.

 

Gary.

 

You made a great point from the sheet Mike posted. You want to write a description so that I could come to your town and find what I am looking for. and I am not from there at all.

 

In closing a quick note. PLSS which is overseen by BLM is about Property lines. It is also called Cadastral survey. And while it strives to be geodetically accurate, and I mean by that while they try to make Cadastral measurements fit within the constructs of Horizontal control, it does not always do this. First, It really does not address the vertical component of a survey well at all and second While Horizontal Geodetic control locates by using Triangulation and Trigonometric least squares adjusted triangles, PLSS used and can still use depending on the age of a survey, Chained distanced from place to place to points where the angle to the next point was turned on a transit. It is sort of linear in the way it was established.

 

Property was never defined geodetically in the first place. It is where it is, so the the surveyor had to describe it by starting at a known place that was a base for Cadastral work, call it a P.O.B. or point of beginning for a survey and describe their way over to that particular piece of land in order to describe that land. It is known to us that if we come to that piece of property from another point of control and with newer more accurate instruments we may not Jibe with the older survey, so we have to compare and accurize as we go. Meaning we find errors and lost survey markers and things that do not fit the world as we are surveying it. Yet we still have to define what we are doing.

 

It was not until later that they tried to make the PLSS work fit in a geodetically calculated world. Even now, PLSS has some fudge factor built in, but Geodetic work does not. On the geodetic side, we need to come up with numbers that compare favorably with those 5 places to the right of a decimal point. Hopefully this explains in a small way that the NGS benchmark is not really related in a PLSS survey and if we were to try and include it, like Mike said, it would be costly as the BM is not horizontally described in the first place, only vertically and the PLSS survey does not really do much with vertical control, as it's job is to describe the location of a particular line or a set of lines on earth. We do need to know both types of information, but they are traditionally described separately, not taken together.

 

Hopefully I have shown a little of how that Bench Mark data is important in a real world way.

 

Good Luck,

 

Rob

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Mike, Rob:

 

I never meant to suggest that it would be practical for a local surveyor to reestablish control for an NGS mark. Nor did I mean to suggest that one NGS mark, all by itself, with or without control information, could be used to reestablish a property marker. I just mean that the NGS mark could be one of many clues to where the property mark should be reestablished, provided it had been referenced on an earlier plat or legal description of the property.

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I got that.

 

What I was saying was that is very unlikely it would have ever been used in a property survey. Although the marks may be been there for 100's of years, they were not widly known about in the private sector. Some gov't agencys knew of them but the private sector had very little knowledge or need to know. Until the later part of the 20th century this info was not much used. With the advent of GPS, more private sector use has been noted.

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Call me silly, but looking at those instructions for setting a "reset" had an interesting mention - that the bags used to mail them are franked. Cool

 

(Franking, for those of you who are not into "stamps" is the right to mail something based upon a signature. Active duty military, and your Senator get to do it)

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