Question about RTN Field Procedure

Well, at least all the monuments were found.

But if someone needs to reset one in the future from his survey drawing, I wouldn't expect it to be as close as it could have been to the old position.

I'm as appalled as you are, but I think know that what you are seeing is common.  What is more, I think it likely that your PLS client doesn't know that it is happening this way. Luckily, with the current state of technology, the coordinates are probably good enough. Whatever that means.

That is really sketchy. Just be glad it's not your name on it at the end of the day. I don't think I would be able to hold back on saying something to that effect to the person staking their name and reputation on it. 

Jim,

Way sketchy.  Call me old school but monuments get a minimum of 180 epochs on two discrete observations.  I like to shoot for four hours between observation. In my 30 plus years of GNSS experience, I can not tell you how many times the two observations don't jive.

What is the issue with preparing the map in the native grid?

That would be an unacceptable cadastral field procedure here in New Zealand - GNSS data should be two sets of observations separated by at least 30 minutes.
While not mandated, for me each set has two measures of at least 60 epochs averaged with a 180 pole spin between.

I will guarantee you that , Joe Fieldwanderer, does not perform up to the goals that have been stated.  The only way those goals will be met is if the PLS takes the time to track exactly every shot taken versus time of day of the shot and then enforces penalties for failure to meet expectation.  Of course, that also dictates that the PLS bill out time accordingly to the client. 

There are shots in the field that may take over 30 minutes roundtrip to access out in the wilds of PLSSia.  Too hot, too cold, too windy, rain is going sideways, too difficult to access, whatever.  It's not going to happen because "we" collectively are not as tough as the oldtimers who had to do it the hardway.  One hundred feet at a time through every inch of obstacles, on foot, teamed with a doofus, all uphill and then the chain breaks and you notice the tripod tilted too far.  Hell, I remember turning a 90 to get back on line by doing a 30-40-50 triangle based on a best guess alignment.  That's how you determined the distance to the center of a center.  Forget that theoretical crap about rossing straight lines between quarter corners.  And, on a curve??????????  What a farce?

Posted by: @john-putnam

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What is the issue with preparing the map in the native grid?

If it was simply a matter of aliquot parts, I might do it on grid.  But this job entails dozens of parcels and exceptions, with a lot of oddball bearings (some parallel with a railroad, some following a creek), so making the comparisons with record dimensions will be simpler (for me, anyway) if it's on a local basis of bearings and using ground distances.

@jim-frame 

"and using ground distances."

AMEN  I detest basing description writing in "in the sky" coordinates.  That can be a far larger descrepancy than being out of level.

Posted by: @holy-cow

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AMEN  I detest basing description writing in "in the sky" coordinates.  That can be a far larger descrepancy than being out of level.

With the new 2022 datum Kansas will have 20 zones, 19 of them LDPs. The difference between grid and ground distances will be small enough to ignore. That may seem like a lot but remember that Oregon has had 39 LDPs for over a decade. 

@jim-frame, in these cases I like to create separate drawing for the various records.  I then Xref them into my boundary drawing.  This way you piece the puzzle together by translating and rotating them onto your found monuments.  When working with SPC coordinates you can even scale the xrefs by the C.F. to bring them to the grid.  If you like record line, then NCOPY it from the xref into the working drawing.

Works great for coming up with search coordinates.

That's pretty much my practice, though instead of XREF I just keep the record parcels on a separate layer (or more than one layer when things are especially complicated).

I’ll make them a block, residing on a separate layer. Makes it easier to keep together.

Posted by: @norman-oklahoma

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I’ll make them a block, residing on a separate layer. Makes it easier to keep together.

Ditto. It amazes me to receive CAD files from other surveyors that don't have separate layers for the record info vs. final boundary determination.

I'm down to three observations, each for 30 seconds with around 20min or more time separation but that's only for NC and SC RTNs where I've tested with static and total station. I've had bad luck with hodge-podge of RTNs in VA and elsewhere.

After all of the years of viewing examples on this site showing higher quality data from base/rover, I've finally switched to that process and just use the RTN as a check on the RTX-PP coordinate that TBC creates from my base receiver's .T04. I should have listened to many of the folks on this forum as any time lost setting up the base has been recaptured by higher precision, particularly under canopy. 

I get very good repeatability with Carlson BRX7s Base Rover pair, even under heavy (but not full) canopy.  I usually occupy a point for at least 30 seconds, sometimes up to 3 minutes depending on how good the solution math 'looks' on the screen.  When I have good confidence on the first shot, I can't remember a time when I didn't get the same results the next time.  Get iffy data the first time, then all bets are off.  I have also seen a point that wouldn't fix 5-15 minutes before return a tight solution in the time it took me to look at how to navigate to the next point or cut a little bit of line thinking I was going to need to run the line in with TS.  The version of SurvPC I'm running has Carlson's SureFix, so it's a double solution from the beginning anyway.

Those occupation times for the RTN are not adequate for a defensible boundary position if there should be a dispute that goes to court. Just sayin'

As for you canopy guys, a word or three of caution. Just because the manufacturer gurus say that you can correctly position under canopy doesn't mean that you can. They have their algorithms and the comparisons available with the various GNSS signals are much better now, but signals bounce and are interfered with by canopy. It's physics. Might want to consider doing a little side measurement with a Disto or offset just to make your stuff defensible as well.

The only way occupation time plays into it for me is this:  I occupy for as long as, or as many time as it takes to get repeatable results.  What I posted above is about that.  Repeatable results.  If I don't get the same answer twice within the legal standards, I redo it or change data collection method and redo it.  Keep collecting data until I'm sure it's right.  And I'm not using RTN.  Always been a Base/Rover guy....

See also what C posted here:

https://rpls.com/forums/postid/594724/

Tight groupings don't necessarily equal good coordinates.