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Can new Benchmarks be placed?

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I'm afraid the phrase "anyone qualified" is overly optimistic and therefore likely to give rise to false hopes. This phrase is technically correct, but in fact very, very few people are truly qualified. I do not wish to be a party pooper, but I can assure you that it is absolutely impossible to meet the NGS requirements using any handheld device. The devices that are used by professionals must be mounted on tripods for stability when doing high precision work. These devices are quite expensive, with basic models at $20k-$30k, and the most precise models at over $100k. In addition to the financial investment, an investment in time, learning to use them properly, usually amounting to several weeks or months of trial use, is also required. So, unless you are prepared to make these investments, you are sincerely advised to dismiss the idea of creating new markers. You can make the most valuable contribution to your community and assist your local professionals by hunting down long neglected markers and providing your results to your local Land Surveyor. If he does not happen to be interested in your findings do not give up - contact your state's Board of Registration For Engineers and Surveyors. They will probably be able to direct you to a Land Surveyor who will look at your information and appreciate your efforts. Best wishes and good hunting!

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To my recollection, only the NGS can place or replace geodetic monuments. Their equipment is more or less, survey grade GPS. It's just more precise than the handheld units. The data has to be processed in order to obtain a balanced coord system. Depending on the accuracy of the monument, on the benckmark data sheets, you'll see a class and order of that particular benchmark.


------------------------------------------------------------If I had a nickel for every sewer manhole I've seen near rivers, creeks, and lakes, I'd be RICH!

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As someone noted, you will not be able to replace any benchmarks for reasons of both equipment and authority. Setting first order benchmarks (levels) requires some serious leveling equipment, some post processing headaches, and patience that tries most mortals.. Even if you have that, the qualifications generally demand a license as a land surveyor or a federal appointment neither of which is easy to get.


Equipment.. actually GPS is never used for benchmark work. The relative accuracy of GPS for vertical work is measured in centimeters.. Precision vertical work is done in less then 1 mm.


The equipment that was shown on the link, is called a Kinematic GPS system. The rover unit is shown and requires a second base or a link to a CORS system (public shared system sorta). With that equipment - as shown (hand held) you can expect to get horizontal values of a couple of hundredths and vertical accuracy of 2 or 3 CM's. The RTK (Real Time Kinematic) system costs about $20 to $30 k depending upon which bells and whistles you want.. Check out Trimbles web site for more exotic stuff.



Last I heard NGS was no longer maintaining ANY monuments.. NOS (National Oceanic Systems) is, but if you are out in the middle of Nevada or Oaklahoma you are going to have to wait for the next 'big one' to get Ocean Front Property and new NOS disks.


Ok.. I've been pontificating again.. sorry..

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Originally posted by ca_surveyor:

The RTK (Real Time Kinematic) system costs about $20 to $30 k depending upon which bells and whistles you want.. Check out Trimbles web site for more exotic stuff.



I am very lucky to live in a town in the Netherlands where there is a firm selling second hand surveyer (GPS) stuff.



where they have a few Leica SR9500/AT302 GPS multistations for only 7.5 K Euro ( is about the same in $$). So let mentioned prices of 20/30 K$ not stop your search.

Look around: somewhere in the USA someone will be selling second hand also!


Prof. Y. Lupardi

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