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1882 US PBM  

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Bill93
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Mike, I thought it was this one, which doesn't have a GPS suitability line.

https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=LD0480

Linebender is a bit further from home than I expected.

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GeeOddMike
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@bill93

While it is unlikely pre-modern surveyors gave much thought to maintaining uniqueness in designations, it is hard to trace information about the multitude of monuments designated “A” or something equally common.

I note inconsistencies between the description and the other fields on the LD0480 datasheet.  It is hardly set in a concrete monument. Now that the datasheets are being updated by external parties, awareness of correct coding seems largely lacking. In this case it was an internal coder responsible. 

I also note that this benchmark was last used in 1952 but participated in a 1991 adjustment highlights the problem with a national vertical network not maintained nor observed regularly. Additional evidence of the need for the new nationwide vertical datum.

Seems to me this would be worthy of a recovery and photo.  

7051CD84 0838 4E17 9E79 BF3336A21555

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linebender
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@geeoddmike

More than worthy.  Also a Shared Solutions mark nearby with reference to the 1882 mark and a leveled height difference in the description.  This will give the best tie possible from the cheap seats to the active and passive system. 

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linebender
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Bill

I can't get too much further away and be in my work area - 60000 square miles give or take.  The 1882 description is more accurate than the datasheet. The datasheet led us astray for a minute or two. That plus the owner had a bench (the kind you sit on) in front of the mark.   Data sheet says AT THE SOUTHEAST CORNER OF THE  INTERSECTION OF MAIN AND CEDAR STREETS. 1882 says on the south corner of Main and Cedar.  It's definitely not SE of the intersection. It is south or possibly SW.  The data sheet lat/long put us 110 ft SE of the intersection. The mark is on the other side of the street. Also Main and Cedar run parallel in town nowadays.  They don't intersect.  Note the difference in height. 167.7492m  1882 river datum vs 161.515m NAVD88.  Looks like Mike one upped me by a few years on his BM. 

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GeeOddMike
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No intent to one-up, I noted your image and recollected the historically significant BM A in Hagerstown, MD. The issue you mention with the description are not rare. I also recollect the effort to digitize BM descriptions as part of the NAVD88 project. The basic process was to use USGS quadrangle maps and level run information to plot the benchmarks then scale the position.

In my previous response I provided a link to a interesting history of US leveling. I captured the information pertaining to BM A below:

 

D90226FF 9D61 49F3 97A1 5074C7782D61

 

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linebender
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Mike

Appreciate the perspective and history.  I found a BM A about 350 miles NW of the subject handsome hewn red granite BM a few years ago. I think it was for the Missouri River survey on a tributary. I have never been able to find any information on it other than the NGS data sheet.

a4

 

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dmyhill
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Posted by: @a-harris

Every construction site I've worked on all the plans were in feet and inch and we always used feet and tenth tape for the layout.

Really? I have never seen a set of civil plans in feet and inches. 

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A Harris
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@dmyhill

Every Internation Paper Co design are in feet and inches.

Done two malls that were, Longview and Texarkana.

Cason, Texas SWEPCO coal power plant was.

All these were that way because much of the designs are to fit prefab steel and other components onto the site.

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