Old NGS NAVD29 Benchmark Datasheets

Probably in a dusty filing cabinet in the basement. I don't think that these documents were ever scanned into a digital format, but I could be wrong (AGAIN). I have several 3-ring binders of the Paper Copies of both Horizontal and Vertical USC&GS Horizontal & Vertical "Control Data" (these are separate forms) for areas in Nevada and Montana. I don't recall why I have the Montana Data, probably related to Gravity Work I did there in the 70s.

Loyal?ÿ?ÿ

I think the data sheets still show the 29 data as superseded - I use an android app - Benchmap which locates nearby points and then pulls up the datasheet for review - it also has some greyed out that have been lost and green ones for marks that have been recovered at some point in time

Here is one I have used

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

1        National Geodetic Survey,   Retrieval Date = OCTOBER 28, 2021
 HT1843 ***********************************************************************
 HT1843  DESIGNATION -  Q 568
 HT1843  PID         -  HT1843
 HT1843  STATE/COUNTY-  CA/SAN FRANCISCO
 HT1843  COUNTRY     -  US
 HT1843  USGS QUAD   -  POINT BONITA (2018)
 HT1843
 HT1843                         *CURRENT SURVEY CONTROL
 HT1843  ______________________________________________________________________
 HT1843* NAD 83(1986) POSITION- 37 45 03.81   (N) 122 30 29.81   (W)   HD_HELD1  
 HT1843* NAVD 88 ORTHO HEIGHT -     7.56  (+/-2cm)       24.8   (feet) VERTCON   
 HT1843  ______________________________________________________________________
 HT1843  GEOID HEIGHT    -        -32.775 (meters)                     GEOID18
 HT1843  VERT ORDER      -  SECOND    CLASS 0 (See Below)
 HT1843
 HT1843.The horizontal coordinates were determined by differentially corrected
 HT1843.hand held GPS observations or other comparable positioning techniques
 HT1843.and have an estimated accuracy of +/- 3 meters.
 HT1843.
 HT1843.The NAVD 88 height was computed by applying the VERTCON shift value to
 HT1843.the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
 HT1843
 HT1843.Significant digits in the geoid height do not necessarily reflect accuracy.
 HT1843.GEOID18 height accuracy estimate available here.
 HT1843
 HT1843.The vertical order pertains to the NGVD 29 superseded value.
 HT1843
 HT1843.Click photographs - Photos may exist for this station.
 HT1843
 HT1843;                    North         East    Units  Estimated Accuracy
 HT1843;SPC CA 3     -   640,742.4   1,823,039.3     MT  (+/- 3 meters HH1 GPS) 
 HT1843
 HT1843_U.S. NATIONAL GRID SPATIAL ADDRESS: 10SEG4331778308(NAD 83)
 HT1843
 HT1843                          SUPERSEDED SURVEY CONTROL
 HT1843
 HT1843  NGVD 29 (??/??/92)    6.729  (m)           22.08   (f) ADJ UNCH    2 0
 HT1843
 HT1843.Superseded values are not recommended for survey control.
 HT1843
 HT1843.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
 HT1843.See file dsdata.pdf to determine how the superseded data were derived.
 HT1843
 HT1843_MARKER: DB = BENCH MARK DISK
 HT1843_SETTING: 31 = SET IN A PAVEMENT SUCH AS STREET, SIDEWALK, CURB, ETC.
 HT1843_SP_SET: CATCH BASIN
 HT1843_STAMPING: Q 568 1939
 HT1843_MARK LOGO: CGS
 HT1843_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY
 HT1843
 HT1843  HISTORY     - Date     Condition        Report By
 HT1843  HISTORY     - 1939     MONUMENTED       CGS
 HT1843  HISTORY     - 1973     GOOD             NGS
 HT1843  HISTORY     - UNK      SEE DESCRIPTION  GEOCAC
 HT1843
 HT1843                          STATION DESCRIPTION
 HT1843
 HT1843'DESCRIBED BY NATIONAL GEODETIC SURVEY 1973
 HT1843'AT SAN FRANCISCO.
 HT1843'AT SAN FRANCISCO, SAN FRANCISCO COUNTY, ON GREAT HIGHWAY, AT
 HT1843'THE FOOT OF ORTEGA STREET, 57 FEET WEST OF A FIRE HYDRANT, 20 FEET
 HT1843'WEST OF THE CENTERLINE OF THE LOWER LANE OF THE HIGHWAY, AND IN
 HT1843'THE TOP OF THE CONCRETE CURB AT A CATCH BASIN.  A STANDARD DISK,
 HT1843'STAMPED Q 568 1939.
 HT1843
 HT1843                          STATION RECOVERY (UNK )
 HT1843
 HT1843'RECOVERY NOTE BY GEOCACHING UNK
 HT1843'RECOVERED AS DESCRIBED.

@rkinnie Absolutely true! At least in the vast majority of cases.

U.S.G.S Bench Marks, not so much (unless they were incorporated into later USC&GS/NGS level lines). I checked a couple of the Montana Bench Marks that I have PAPER sheets on, against the current NGS Data Sheets, and BOTH the NAVD29/NGVD29 Elevations and the "early" Monument descriptions were verbatim. In my experience, that can be considered the norm.

Loyal

@loyal They are on the USGS topos. Those show are too the foot. Once you convert them from NAVD 29 to NAVD88 the agree better with OPUS than the newer ones NGS show.

USGS NGVD 29 benchmarks

I know-Not NGS but the USGS leveling ties to the old 29 NGS BM datum. Around here there are many USGS tablets not in the NGS database.?ÿ

Posted by: @skeeter1996

@loyal They are on the USGS topos. Those show are too the foot. Once you convert them from NAVD 29 to NAVD88 the agree better with OPUS than the newer ones NGS show.

That's a confusing comment. Where are the newer ones coming from if not a datasheet??ÿ

Accessing NAVD88 or 29 datum via CORS does not equal accessing NAVD88 or 29 via passive marks.?ÿ

USGS marks that NGS has not tied/used are paper ONLY and you would need to contact the USGS.

SHG

@shelby-h-griggs-pls I think you are right. I have gotten information from the USGS about the Corner evidence when they showed a BLM corner as being found on a USGS Topo.

Posted by: @shelby-h-griggs-pls

USGS marks that NGS has not tied/used are paper ONLY and you would need to contact the USGS.

SHG

Right on Shelby!

Back in the day, I had a phone number for THE USGS GUY in Denver who I could call to get copies of the USGS Bench Mark Data. As I recall, it was indexed by the Southwest Corner of 30 minute quads (not maps, but 30 arc minutes of Latitude & Longitude). I have a bunch of that data (somewhere). Depending on the date of the Leveling, you can sometimes find USGS Bulletins that have the data and descriptions (prior to about 1938 or so, much earlier in some states)

Loyal

@norm Their elevations are published on the USGS topo maps. However the datum they are based on is NAVD29. To check into them using GPS you have to convert the NAVD29 elevation to NAVD88. They have nothing to do with CORS.

The old Benchmarks shown on USGS topos usually aren't shown in NGS's Survey Data Explorer. They should be, they are as accurate as the ones that are shown, maybe better,

Posted by: @skeeter1996

@norm Their elevations are published on the USGS topo maps. However the datum they are based on is NAVD29. To check into them using GPS you have to convert the NAVD29 elevation to NAVD88. They have nothing to do with CORS.

The old Benchmarks shown on USGS topos usually aren't shown in NGS's Survey Data Explorer. They should be, they are as accurate as the ones that are shown, maybe better,

That depends on what you mean by "accurate."

If you mean that they agree with everything in town, it's probably because the Town Datum is based on the USGS disk in the steps of the Court House or Post Office, and the approximate (unadjusted) elevation stamped into it by the leveling crew a century or so ago.

Loyal

Posted by: @skeeter1996

@norm Their elevations are published on the USGS topo maps. However the datum they are based on is NAVD29. To check into them using GPS you have to convert the NAVD29 elevation to NAVD88. They have nothing to do with CORS.

The old Benchmarks shown on USGS topos usually aren't shown in NGS's Survey Data Explorer. They should be, they are as accurate as the ones that are shown, maybe better,

I was referencing your statement about passive marks agreeing with OPUS (CORS)?ÿ

My experience is if the marks aren't in Explorer they aren't NGS marks. Thus my link to USGS marks.?ÿ

Sorry,?ÿ but the repeated references to "NAVD 29" are making me nuts. The 29 datum was NGVD. What am I missing?

Posted by: @thebionicman

Sorry,?ÿ but the repeated references to "NAVD 29" are making me nuts. The 29 datum was NGVD. What am I missing?

It's late - NGVD is what I mean.?ÿ

Plus I have one eye on the football game.?ÿ

Posted by: @thebionicman

Sorry,?ÿ but the repeated references to "NAVD 29" are making me nuts. The 29 datum was NGVD. What am I missing?

In 1973 the "Sea Level Datum of 1929" (sometimes referred to as NAVD29 erroneously), was renamed the National Geodetic Vertical Datum of 1929 (NGVD29). I don't know where the "NAVD29" moniker originated, but prior to 1973 it does show up in some documents (not NGS ones).

I'm with you, it makes me a little crazy too, which is why I used NAVD29/NGVD29 above.

Loyal

Posted by: @thebionicman

Sorry,?ÿ but the repeated references to "NAVD 29" are making me nuts. The 29 datum was NGVD. What am I missing?

Thank you

https://www.xyht.com/surveying/did-you-know/

?ÿ

?ÿ

@thebionicman?ÿ ?ÿ NGVD came about on 10 May 1973 When NGS gave it that name. Please see the following that might explain it. I think the 3rd par. down is the real reason.

ngs.noaa.gov/datums/vertical/national-geodetic-vertical-datum-1929.shtml

When you get to that write-up and read it then click on Vertical Datum's on the left side and that will give you more information and Dates. (interesting). Hope this helps.

JOHN NOLTON

@loyal?ÿ

I am not sure who scanned them, but I have all of the USGS horizontal (traverse and triangulation) and vertical (leveling) "books" as pdf files, arranged by 30' quads as Loyal says, for KY, MD, NY, OH, PA, and WV. Typically these are third order control. I got them from a NGS regional advisor.?ÿ

Total files are 1.3 GB

It really is a shame that these are not available nationwide. As Loyal says below, while they are not of the same accuracy as the NGS marks, and are only NGVD29 (and NAD27) they are often what was used to provide control for towns, dams, etc.?ÿ

If anyone needs some of these, let me know.?ÿ

?ÿ