PLSS Cap MarkingPosted by ridge on April 28, 2012 at 7:20 pm
How should this point be marked?
It’s a quarter corner on the township line (not standard parallel (13S/14S). The corner is in a county road (east/west – gravel). The county doesn’t want the marker in the road because of grading. I’m still going to set something buried 18 inches under the road probably a DuraNail and fender washer with my name and number on it and a DEEP-1 magnet. Somebody might need to dig it up someday.
So I’ve decided to place the County Cap on the quarter section line north of the actual corner probably 1 rod which is at the ROW line. The marker will be on line so I’m thinking it should be a Witness Corner (WC) but it is not on any original survey line (run on the ground). So I suppose it could be a Reference Monument (RM) or maybe a Witness Point (WP).
A complete record with photos will be filed.
What would you do? WC, RM or WP? Does it matter?
- 10 Replies
- MemberApril 28, 2012 at 7:27 pm
I’d probably go with Refference Monuments (2), one on each side of the road. That’s the way the BLM has done it in the past (at least sometimes).
- MemberApril 28, 2012 at 7:40 pm
I like to set 4 references, not on line but one in each quarter. I want a good intersection as close to 90° as reasonable. Forces those following to actually do an intersection, based on measured record distance. Four references allows for a check, even if one is destroyed.
- MemberApril 28, 2012 at 7:43 pm
Good point Jud!
More is always better than less, especially when things start to “go away.”
- MemberApril 28, 2012 at 8:18 pm
The marker(s) will be aluminum pipes and 3-1/4 caps. I don’t think four are necessary. I suppose you could tie it out 4 ways to bearing objects. What I been doing is running 6 hour (or more) OPUS sessions. Part of my documentation is the OPUS solution printout. I’ve offered to provide the RINEX file but they don’t want it (State GIS – AGRC).
It will be hard to do a long session in the middle of this sort of narrow road (block the road). I can do the RM’s but two should be plenty in my view. The common practice around here seems to be placing double headed nails in fence posts for tie outs and I refuse to do that at all (not stable or permanent enough for me).
I might take some heat for this but I think the long OPUS session is good enough without tie outs even with a couple cm slop in putting it back (out in the rural area). That’s why I was thinking one WC tied underneath and the corner point marked underground. But I’ll probably go with two RM’s each tied directly underneath with DuraNail/washers and then the DurnNail/washer buried in the road. Each RM will be observed with a long session probably both at once. So I have three holes to dig in rocky hard ground, anybody want to help?
- MemberApril 28, 2012 at 8:32 pm
Here’s one example of how the BLM does it.
It’s nice to have at least two since you’re along a road and things just seem to get disturbed along county roads-around here anyway. They usually put them at an angle at nore or less 90.
RM is what I’d call them.
- MemberApril 28, 2012 at 8:49 pm
Makes no difference if it’s an original line or not. If you’re setting it on the N-S C-C line it’s a Witness Corner i.e. WC. If you set it at something other than that it’s a RM. Since you are providing records etc. You can call it whatever you want, I’d be tickled pink just having a good record to go off of.
- MemberApril 29, 2012 at 1:52 pm
I have one where they set them opposite each other, e.g. N30E and S30W ~ 50 links.
And the monument is there too but it is buried about a foot under the shoulder of the dirt/gravel road.
The big arrow doesn’t matter; the Foresters will run their flagging to it anyway.
- MemberApril 29, 2012 at 3:28 pm
An idea whose time has truly come. :angel: I have no idea why we insist on placing surface marks in roadways that get resurfaced periodically-not to mention the safety aspect. B-) Why do we continue to put ourselves and our employees in harms way needlessly. :stakeout: RM’s done as you suggest will allow sufficient location of the corner. I know there is still a fair amount of resistance to the idea. :woot:
(the faces are put in this message at the insistence of my 6 yr old who is watching me type.):-$
- MemberApril 30, 2012 at 12:57 pm
I would set two reference monuments. Witness Corners are usually set where you can never occupy the corner location, such as off of a cliff. Reference monuments are used when you can temporarily occupy the corner position such as a road. No matter what you call the monument if you only have one you are requiring that a subsequent surveyor to get some basis of bearings before figuring the corner position. With two reference monuments a subsequent surveyor can always do a distance-distance intersection. You can mark the reference monuments with the full corner monuments and add “RM”, or you can do just a rebar and cap. I like to at least have the letters RM, an arrow pointing to the corner and a distance, this way it is obvious that the RM is not the corner point. Also, don’t call the reference monuments on a survey line, this causes extra retracement work. Try to put them as close to 90 degrees as possible.
- MemberApril 30, 2012 at 7:11 pm
It does matter in my humble opinion.
A Witness Corner is used as though it were a mark that permanently replaces an ‘un-occupiable’ corner location. Highways can be considered to fit into that category. If you set a witness corner it is now “the” monument. If someone accepted your corner, and had to run math off of it, they use and rely on the witness corner and not the mark under the asphalt. Setting something in the road can be a safety issue as well.
If you go with a witness corner, I recommend using 4 reference tie accessories to that mark so they (the accessories) can be used to replace the witness corner monument. If someone needs to proportion in a corner they would use the witness corner for their proportionate distances; and shouldn’t have to dig up your marker in the road.
If you go with reference marks then, I agree that they are best to be perpendicular to each other and off line. I would take 4 reference ties to each of those as well. If someone is trying to retrace your work, they need to find out where your witness corner or reference marks once were. I like using each reference mark as a one of the tie-accessories to the other reference mark.
(by the way, there is something called an ‘off-line witness” mark as well. I think there are standards for how far from the theoretical corner they are, is also an issue.)
(finally, re: “highways fit into that category.” I think it’s more important to get monuments out of busy roads than it used to be. It is a danger issue that is not worth dying for. Highways are much busier now than when they started the PLSS system and vehicles are made of steel and drive much faster then when they first started to make roadways. Standards today should reflect the danger and problems with surveying inside of busy roads.)
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