68-eldo
-
Posts
355 -
Joined
-
Last visited
Posts posted by 68-eldo
-
-
Reference marks with PIDs are almost always bench marks (vertical control stations). Typically a tri-station and several reference marks are set (say in 1930) and then later (say 1956) the CGS will run a level line through the area and use the reference marks (and sometimes the tri-station itself) as bench marks (vertical control stations). Having a nice solid disk at a convenient location saves them time and money with their leveling.Does anybody know why reference marks with PID's are dropped from the data base? I frequently encounter "No Mark At This Location". Yet, when I follow the box score (distance and bearing), the reference mark is there--exactly as described.
Example:
Ref Mark 1 for EZ1426. I calculated the coordinates using NGS FORWARD, and walked to the spot, using my GPS display. Found it immediately with the metal detector--flush with ground but covered by leaves.
-Paul-
Examples are the two RMs for station PALISADES (KU3890) which have separate PIDs: KU1644 and KU1645. Look at the dates and you will see the leveling was done in 1956, quite a while after reference marks were set (1930). You will also note the the coordinates of the RMs on the sheet are scaled (and in this case very far off - you wonder why they just didn't use the coordinates of the nearby tri-station). I have never seen an RM with a PID with adjusted coordinates.
So it's quite possible the RM's PID was dropped due to loss of control or other problems with the vertical control. The "net" they belong to is independent of their role as reference marks.
AH HA! That explains it. I was wondering why some RMs have their own PID. Thanks for enlightening me.
-
68-eldo--I haven't asked for permission to get onto someone's roof. There aren't any marks like that around here. I would be surprised to get permission to go somewhere like that, although my technique would be to ask them when a good time to be escorted to the roof might be. If you get the right person you may just get up there.
I did consider it to be a longshot. If I lived in that area I would try with a letter to someone in charge and ask for a time and date. If there isn't any response I would try talking to the maintenance crew, see if I could get one of them to take me up there.
But this is Klemmer's stomping grounds maybe he should make the assault er I mean attempt.
-
68-eldo
FYI, I can't get any of the links to work now.
Apparently the owner of the web site has not paid his bill for hosting. The domain name is paid until Dec. 3, 2007. I hope he pays. It was a good web site.
I contacted the owner of the web site John N Shankland and he told me he was having problems with the hosting service. But it has been resolved and the web site is up again. Thanks go to Mr. Shankland for the web site and his efforts to keep it up.
-
I haven't said this in a while so I will reiterate it (and hopefully will NOT jinx myself). I have hunted for just short of 1,600 benchmarks and have NEVER been refused permission to hunt on private or commercial property. Granted, I haven't had to ask for permission every time--but I bet I have asked well over 100 times.
Yeah, I will be out again this weekend!
Interesting. The first time I needed to ask permission I was refused. I wanted to log DX4789 and DX4790. I went to the front desk in the building and told the man that I am a volunteer checking on the condition of the marks. I even showed him the NGS data sheets.
Maybe I need to work on my presentation. Or maybe my urban camouflage.
-
68,
The height, or length as you stated is improtant and that is why Paul mentioned that he had been putting the height of the rod in when it did change. The software uses the rod height to calculate the elevation down to the point. Remember this is a resource GPS and elevations are going to be an approximation; I doubt that Trimble will even state what the elevation accuracy is for this unit. I would expect it to be in the neighborhood of ±10', but that is pure speculation.
As to his horizontal accuracy, that is going to be relative to how accurately he held the rod plumb. Generally you use a bi-pod to keep the rod plumb for the GPS session while using a rod; for static survey grade sessions, the best method is to use a tripod. For precise measurements it is also a function of the calibration of your equipment, as in checking to make sure your rod is truly plumb. So you are right, if the antenna is not precisely over the point the measurement will be wrong.
CallawayMT
Thanks Callaway.
I assume there is a bubble level or some such to show the rod is plumb.
-
One thing I am curious about is how does this receiver get that kind of accuracy when the antenna is 5 feet or more above the point being measured? If the antenna is not precisely above the mark then the measured point would be wrong.
Also I believe the length of the pole would also be important to the calculations.
-
I would like to post a benchmark entry at the geocache.com site for the following marker I found, but I don't know the exact GPS coordinates and I can't seem to find a map that would give them to me for this particular survey. It is 10 miles outside of Palm Springs, CA and quite off the beaten path. I am a complete newbie here and would appreciate any help you folks may have to offer.
Check out this web site. It will give you a Lat. Lon. for the center of the section if you put in the State/Meridian, township, range, and section.
It provided the following info and more for the above mark:
Latitude/Longitude 33.7231°N, 116.5174°W ( 33°, 43', 23.0" N; 116°, 31', 2.8" W )
The legal description is: California, San Bernardino Meridian T5S,R4E,sec24
UTM zone 11 (X,Y) 544708 , 3731556
-
68-eldo
FYI, I can't get any of the links to work now.
Apparently the owner of the web site has not paid his bill for hosting. The domain name is paid until Dec. 3, 2007. I hope he pays. It was a good web site.
-
The shipyard where I worked (also a Civil Service organization) had a “holiday shutdown”. It was designed as a cost cutting program. We were closed for all but highly important work from Christmas Eve through New Years Day. Maybe NGS has adopted something similar.
-
I've found this bottle and earthenware cone situation curious also. Unfortunately surveyors can't find bottles and earthenware cones with a metal detector. Of course back, then no one would've predicted a metal detector technology. The curious thing to me is how was anyone expected to recover these markers for use long ago? It seems that one would essentially have to re-do the survey in order to just find the place to dig! Could it be that these bottle and cone markers were never really expected to be recovered and were just intermediate points that had to be made to connect primary stations?
From somewhere in the far corners of my memory I seem to get the impression that property corners were marked with rock cairns. I would imagine that surveyors would use a cairn as a surface mark. But that is a guess on my part.
-
I agree that there is no significant harm and also definitely agree that it does give you some idea as to the accuracy of your own GPS receiver.
On the other hand, I think that such a reading is not useful log information, including it in a log would amount to pointless clutter, and most importantly, it would just be misinformation compared to the adjusted coordinates.
Handheld (GPSr) coordinates for a location-scaled mark are somewhat useful and the NGS has indicated (I forget where) that it is considering putting fields for that on its mark recovery form. I have no doubt that they would not allow/accept input of coordinates for location-adjusted marks if they did that.
OK, I’ll go along with that. I agree logging the GPSr coordinates of a location adjusted mark in the NGS database is needless clutter. GC.COM is another story.
-
If the benchmark is location-scaled, then if you like, you can post the coordinates of it that you read from your GPS receiver when you find it. Don't do this for location-adjusted marks.
I'm curious as to why you say don’t do this for adjusted marks. I understand some people would consider it a waste of time because the hand held accuracy is lower than the accuracy of the posted coordinates. But I can’t see any harm and in a sense it checks the accuracy of your GPSr.
-
I'm a relative newbie to benchmarking, but based on what I've seen in the Maptech TNPro program, I think the majority of USGS benchmarks are included. It may vary depending on geographic region, but below is a screenshot from a map in south Texas where all BM symbols correspond to NGS entries, which are shown by the red triangles. You can click each red triangle in the software to see the datasheet entry in the NGS database.
You're fortunate. Hawaii is littered with little Xes and dotted triangles and squares, but I've found very few in the databases. :/ I'm finding plenty of other anonymous bolts, pins, pipes and stakes stuck all over the place in the lava, as well. I'm always trying to dig up the history of these things.
Are you talking about Xs on the Topo maps or on the ground?
Survey crews on Oahu seem to make a lot of chiseled crosses on sidewalks or in the road for their construction project. I doubt you would find any information on these except in the plans of that project.
I find most of the Xs on the topo maps correspond with an NGS benchmark and the triangles with triangulation stations. Which is what I would expect.
-
Ooooooo...so THAT's what "Baseline" in Boulder is all about. I lived there a few years and never heard about it being the border between Kansas and Nebraska territories.
It’s interesting how many initial points are near the intersection of Baseline and Meridian Road.
I was born in Boulder. I also wondered about the name of Baseline Road.
I have a KML file for Google Earth posted here that shows all the Initial Points. You maybe able to “save as” or you may have to select all, copy and paste into notepad than save as a KML file.
Corrections and updates welcome.
-
Hawaiian coins? Are these souvenir items or legal tender? Either way, could you post a photo?
-ArtMan-
I can guarantee these would not be legal tender. Hawaii has used American money since the overthrow of the monarchy in 1893.
-
Hmmm….I checked my file two different ways and did not find a point that had a web page on Principal Meridian Project that was not in the Google Earth file. I checked the Wind River Meridian and the web link was on my file and on my web page file. If you can point out any that are missing a link I would appreciate it.
I should also point out that the coordinates have not been verified by me and I am pretty sure that some are not very accurate. Willamette for example seems to be off by about 0.2 miles. It shows up in a plowed field between two houses. I would appreciate any updates on these points.
68,
The reason I did not see the Wind River Meridian, is because the coordinate on the PM Project page is wrong and you used that; it puts it in Montana and not Wyoming where I was looking.
WGS84 coords are: N43 00' 41.0"
W108 48' 51.6"
from my visit.
CallawayMT
Now that was a significant error. Thanks for the correction.
That page is the only source I know of for coordinates. If anybody has a better (as in more accurate) let me know.
-
Hmmm….I checked my file two different ways and did not find a point that had a web page on Principal Meridian Project that was not in the Google Earth file. I checked the Wind River Meridian and the web link was on my file and on my web page file. If you can point out any that are missing a link I would appreciate it.
I should also point out that the coordinates have not been verified by me and I am pretty sure that some are not very accurate. Willamette for example seems to be off by about 0.2 miles. It shows up in a plowed field between two houses. I would appreciate any updates on these points.
Wind River is there for me. I was sure that San Bernadino didn't have a link. That is the one I checked and was referring to....but it is there plain as day now so I must have mis-remembered.
Sorry if I caused you unnecessary work.
The Willamette Meridian gets a lot of geocacher traffic so the geocaching page might have more accurate coordinates for your file. Willamette Meridian While scanning the logs I saw three that left hand held GPSr coordinates in there logs. There might be photos in the gallery with GPSr units as well. I didn't check those.
PID for that one is RD3152 and the coordinates are N 45° 31.170 W 122° 44.631 if anybody wants to correct their copy. I will update my webpage.
Thanks for the input.
-
Hmmm….I checked my file two different ways and did not find a point that had a web page on Principal Meridian Project that was not in the Google Earth file. I checked the Wind River Meridian and the web link was on my file and on my web page file. If you can point out any that are missing a link I would appreciate it.
I should also point out that the coordinates have not been verified by me and I am pretty sure that some are not very accurate. Willamette for example seems to be off by about 0.2 miles. It shows up in a plowed field between two houses. I would appreciate any updates on these points.
-
I am sure there used to be a benchmark right on the sidewalk at the corner of Long Street and Riley Rd on FT Bragg NC but I couldn't find it today. I only found the concrete base where I think it used to be. I am a brand new geocacher and only noted it in passing a few months ago so I didn't pay much attention to it when I first saw it. Is there anyone here that is on FT Bragg and knows of the mark I am describing?
OK I found the intersection of Longstreet Rd. and Riley Rd. I did a search on geocaching.com and found the nearest “benchmark” is an intersection station, not a disk. So most likely the mark you are looking for is not on the NGS data base and therefore not in the geocaching.com database either. There are many marks placed by private surveying companies, city and state governments, as well as federal agencies that are never entered into the NGS database.
-
If anybody is interested I have posed the KML file for the Initial Points here.
You will have to copy and paste into notepad and save as a KML file. Then you can open the file in Google Earth.
Let me know how it works out for you.
-
I got that 100 meter tape from Harbor Freight and used it once--the ring on the end of the tape is plastic and snapped the first time I used it, which made it completely useless for me as I usually jam a spike in the ground through the end hole of the tape so I can run a measurement. I guess I could try to fix it somehow but I just haven't bothered. It is on the floor of my car where I tossed it the day it broke. Also, even if the ring HADN'T broken I think it would have a tendency to slip off the spike unless the spike was angled backward to prevent it.
Now I just do what I did before I had a metric tape--pace off meters or convert them using the calculator on my Garmin (I multiply meters by 3 to get feet, then use that value as inches and add it to my feet value, since a meter is about 3 feet 3 inches. This seems accurate enough for benchmark work. So if a measurement is 14 meters I end up with 42 feet plus 42 inches, which is 45 feet 6 inches. I guess I could memorize the conversion factor, but I stink at that sort of thing and my technique works fine).
Thanks for the feedback about the Harbor Freight tape. Some of their stuff is good but some is junk. It looks like this tape is in the latter category. I wont direct people to that tape anymore. I think this is the tape I bought. It works well but like I say it has feet and inches on one side and feet and tenths of feet on the other. The two sides are different color so you are more likely to notice if you are on the wrong side of the tape. But it does not have metric on it. I carry a project calculator by Craftsman in the truck that does the metric to SAE conversion. The calculator cost $14 on sale.
-
I have a 100' steel tape (a Stanley) which is OK but I would like to get something with both metric and english units. The only thing I found was a 10'/3M tape which is of course too short.
I was thinking of a surveyors supply house but then I realized they probably don't even use tapes anymore. Everything is electronic, lasers, etc.
Any ideas of where to look?
I bought a 300 ft tape at Lowes for less than $30, but it has feet and inches on one side and feet and tenths on the other. I see Harbor Freight has a 330 Ft SAE and Metric tape for $20. I have not used it or even seen one so I cant say how good it is.
-
-
Here's a map of the Principle Meridians and Baselines of the PLSS
I got seriously side tracked with that web site. I went to the home page to search for a list of the initial points with lat lon thinking it might be a neat thing to add to Google Earth and/or GSAK. But I got started looking up land patients of my ancestors. I got interesting results. I recommend it for those that might be interested in their family history.
I never found the list of initial points.
First time Bench Mark hunter need help.
in Benchmarking
Posted
You maybe right about the roof. Reinterpreting the image it does look like the roof may slant down around the edges. Google Earth can get a better look. Reading the description the marks are mounted in a cement slab which I assumed was flat. Both of those marks I believe are triangulation stations that I assume were meant to be occupied. Would they put marks in a really dangerous place like that? I understand railroad bridges because that danger can be mitigated by coordination with the railroad. But to put them where you need sky hooks……
Hope I was not the one to jinx you mloser. Sorry if I did.