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Metal Rod Bench Marks?????


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That is a water shut-off IMO (EF1264)!


Does not resemble any NGS mark that I know of.


Older rod marks are copper clad steel set inside a 6-inch iron pipe and may or may not have a survey disk fastened to the top of.

Edited by Z15
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Rebar with caps anymore


Non Stainless-Steel and rebar are not good for use as bench marks.


Rebar (re-enforcing steel for use in concrete) has ridges to grip concrete, those ridges will also grip the earth and corrode. If the earth moves with frost, so will the mark.


So if you find any steel rods you suspect are a bench mark, chances are good you may have the wrong mark.


I am aware of some old Tri-angulations marks that are iron pins but those are mainly from back in the old days. Modern geodetic work will avoid using iron if at all possible.

Edited by Z15
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Our new Dutch markers that are to be used by surveyers with their professional GPSr and have millimeter accuracy (and height) are made of a rod of stainless steel about 170 cm long that has a kind of shipscrew on the end. They are screwed into the ground. until the top is below the surface. Then a concrete protection with a lid is made. Like this one here that you see in use:


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I can tell you that the travel bugs would travel alright. If a Government or Municipal Surveyor looked in there, that would likely be the last time they were seen. Not so much out of arrogance either, they would simply be doing their sort of maintenance on the station... We all routinely clean out what we find in these things. It is just the way it is.



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