Mark Condition Reports, Exact Meaning: Good, Poor

[+Black Dog Trackers]

(From a March 5, 2004 thread)

 

This question applies to reporting the condition of survey marks on both the NGS site and the Geocaching site.

 

What is the exact meaning of the two NGS condition choices?:

* Good

* Poor, disturbed, mutilated, requires maintenance

 

I looked at the NGS Mark Recovery Entery site and found no definitions of these.

 

Does the difference between Good and Poor refer to the general appearance of the survey marker, or to its worthiness for use?

 

Many disks have nicks and scars of various kinds on them, but it seems to me (I'm not a surveyor) that they are perfectly useful anyway if:

the central mark is still defined

the disk isn't out of position; tilted over, etc.

the disk is identifiable

 

It's designation is mostly unreadable, yet identifiable, especially by local surveyors. Should its condition be reported as Poor or Good?

 

This whole question runs right into the much discussed Destroyed definition (or lack thereof). What is the exact difference between Poor and Destroyed? Is it different for location-adjusted marks and altitude-adjusted marks? There's a continuum from Good to Destroyed. What are the boundaries?

 

The NGS definition: "Poor, disturbed, mutilated, requires maintenance" makes me wonder - what kinds of maintenance are done on survey marks (or other kinds of marks)? What indicates the need for such maintenance?

 

Is this really insignificant, and we should just pick what we feel about the mark? The NGS has the choice of Condition and so I figured it must have some significance.

 

===============================================

 

After asking this question, I got some 'working definitions' from 2 surveyors, Kewaheh & Shark and elcamino.

 

To assimilate from what elcamino and Kewaneh & Shark said,

 

Good - the station mark has not moved or tilted from its original setting, and in the case of a marked disk, the mark's point of reference (central point marker) is clearly identifiable and the disk's designation is sufficiently legible to identify it.

 

Poor - there is some evidence that the station mark has tilted or moved from its original setting, making the mark possibly unusable for precise surveying work. If the mark is a disk, its condition is also Poor if its point of reference marker is no longer clearly defined or the designation is not suffiently readable for identification.

 

Destroyed - the amount of movement of the mark from its original setting renders the mark unquestionably unsuitable for surveying. In the case of a disk, the disk is missing.

 

I'm still surprised that the NGS doesn't have definitions of Good and Poor on their website, and perhaps DaveD or someone can give the official definitions.

 

============================================

 

In response to a re-phrased question of March 30, 2004, Deb answered with:

the Good vs. Poor condition codes can be somewhat of a dilemma because there's some judgement call involved with some of them. If you find a station that has NGS control on it and the condition seems to be questionable then send me a photo via email and we'll work together to determine it's code. I hope I haven't made this confusing. If a setting is stable and the stamping is good enough to identify the station by name but the disk face is marked up I'd call it GOOD. If a disk is still in it's setting but the setting removed it's destroyed. If a disk is gone but the shank remains it's technically destroyed BUT the position might still be usable. I'm sure some of those are listed as destroyed in the database and if you find any let me know because I'd like to change that code to POOR and add an explanation in the text.

 

So, returning to the 'working definitions',

 

Good - In the case of a marked disk, the mark's point of reference (central point mark) is clearly identifiable and the disk's designation is sufficiently legible to identify it, even though the face of the disk may be marked up.

 

Poor - three cases of Poor:

 

1. If there is some evidence that the station mark has tilted or moved slightly from its original setting, making the mark possibly unusable for precise surveying work, report it as Poor.

 

2. If the mark is a disk, report it as condition Poor if its point of reference marker is no longer clearly defined or the designation is not suffiently readable for positive identification.

 

3. If a disk is gone but the shank remains it's technically destroyed BUT the position might still be usable, in which case, it could be logged as Poor.

 

If there is any question between Good/Poor/Destroyed condition for a particular mark, a photo of the mark should be addressed to the NGS in email and the final reported condition will depend on report-condition-negotiation with the NGS.

 

Destroyed - if a disk is still in it's setting but the setting is moved or removed, it's Destroyed.

 

NGS - are these definitions of Good Poor, Destroyed OK for us to use? Are there any differences for reporting non-disk marks?

[qwiffpop]

Blackdog,

 

when I do recon I use those definitions and they work great. It is alot of judgement on your part but adding a statement in the recovery note about the exact nature of the problem is very helpful to us in here (office). We generally wont use a poor quality mark for surveys unless we absolutely have to. But if you stick with these guidelines it aids the surveyors alot. If you see the remains of a concrete post lying in the area where the mark was supposed to be, and the concrete has indications of a round disk in it you can feel pretty good about calling it destroyed, although you have no disk in your hand to prove it. Your judgement, but in your recovery note state the disk was not recovered but concrete post remains were found. This sets of bells and whistles in the suveyors mind that it will not be worth his/her time to go to this location and can move on to the next solution.

[caseyb]

After checking with various people I can say a few things:

 

For the most part, this is a judment call. If the station is readable, stable and looks pretty similar to how it looked when it was monumented, it is good. If it is beat up badly, like say a lawn mover has hit a few hundred times, or is obviously disturbed, it is poor. If you can hold it in your hand, and then toss it to your friend, it is destroyed.

 

As far as mark recovery goes, your only options are really "good", "not found" and "poor". Unless you can hold it in your hand, or it is obviously destroyed (like that tower that was destroyed when a plane crached into it a little while back) you have to work with those options.

 

I looked around and tried to find an "official" NGS specification on what the difference between good and poor is. But it does not exists (so I am told). You will have to use your judgement.

 

Hope that helps,

 

-Casey-

[joegeodesist]

This ain't a beauty contest; the only thing that really counts is LOCATION; is the mark in the same geometric address that NGS measured it to be? My definitions:

 

GOOD -- Recovered as described on the datasheet; looks healthy and happy.

 

POOR -- Recovered, but shows some alarming evidence of damage or movement. Often the marks can get run over, or frost heaved, or the ground is just too soft to support it. If the mark is scarred and leaning, thrust up from the ground like a mushroom and/or surrounded by tractor ruts, it's poor. If the disk is gone but some evidence (stem) remains, then it could still be useful; that's a POOR too. Describe the problem you see.

 

NOT FOUND -- I can't find it. Describe how hard you looked or confused you were, e.g., "not found after 10 minute search; unable to recover because all witnesses are destroyed" or "not found; existance doubtful, entire area is now a new shopping mall."

 

DESTROYED -- We prefer the more optimistic "NOT FOUND" above unless you have direct first-hand evidence that the mark is completely obliterated.

[Bill93]

When the face of a disk has been damaged but is solid in its mounting, how well can the surveyor reconstruct the position? If the circumference is well defined and undistorted is that adequate to define the center position even if the original center mark is obliterated?

 

If the disk is for elevation, I wouldn't think you would care much about a center mark. The important property is the height of the domed disk. But how hard will the surveyor work to measure the amount of height removed from a scraped disk like LE0221? (I reported this one as POOR).

 

Part of the judgment on a damaged disk is whether it can be identified with reasonable certainty. I would contend that LE0221 can be identified because it is clearly a US CGS disk (and unlikely to have another CGS disk nearby that is not in the data base), is in the remains of the described bridge on the right road, and within the usual tolerance for scaled coordinates. I would not make a similar claim for an unreadable disk when looking for a USGS disk in a concrete post without very precice landmark ties.

[caseyb]

When the face of a disk has been damaged but is solid in its mounting, how well can the surveyor reconstruct the position? If the circumference is well defined and undistorted is that adequate to define the center position even if the original center mark is obliterated?

 

If the disk is for elevation, I wouldn't think you would care much about a center mark. The important property is the height of the domed disk. But how hard will the surveyor work to measure the amount of height removed from a scraped disk like LE0221? (I reported this one as POOR).

 

Part of the judgment on a damaged disk is whether it can be identified with reasonable certainty. I would contend that LE0221 can be identified because it is clearly a US CGS disk (and unlikely to have another CGS disk nearby that is not in the data base), is in the remains of the described bridge on the right road, and within the usual tolerance for scaled coordinates. I would not make a similar claim for an unreadable disk when looking for a USGS disk in a concrete post without very precice landmark ties.

Keep in mind that while these discs are "extremely" accurate, we are still talking about +/- a few centimeters of error. Any scratches or dents would be on the order of a few millimeters I suspect. Thus I can't imagine that any surveyor is going to try to measure the "height removed from a scraped disk". The elevation is still accurate, because the amount of "height" removed from a scrape would fall inside the margin of error.

 

-Casey-

[+Nazgul]

(edited and moved post to different thread)

Edited February 17, 2005 by Team Nazgul