Field Procedures for Setting Boundary Monumentation by GNSS

I'd say 98% of our boundary mons are set by total station, but if we are doing it with GNSS, it's with a local RTK base, and after setting each monument they are always observed using static procedures with minimum of two separate baselines to known control. Network adjustment performed for analysis.

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Most rigorous method I have used??ÿ Dual RTK + logging bases on two primary control points, usually at least one other static receiver running as well.

Using first base, stake to point, dig out hole, position post mon, backfill and stabilize. Place temp mark on cap, switch to second base, place second temp mark, split the difference and punch it. Set up tripod over the permanent punch and observe two 15-minute static sessions, changing receiver height in between.

Process static for all set mons and run full network adjustment to obtain final positions, compare against calcs, if they're out of tolerance, go back and reset.

Probably not the best way, but I set the iron rod and cap with the instantaneous stake out reading; then record with the longer epoch documentation shot; then adjust the iron rod and cap based on the recorded error and record again. I have expanded my error ellipse for the type of monumentation to anything less than 0.02' by 0.02'; again, probably not accurate enough. Most of my monumentation is set with Robotic TS.?ÿ?ÿ

Get a Javad. After setting the rod, record 5 shots on it. As long as 3 of them are within a 0.2'?ÿ radius of the stake coordinate you are golden.?ÿ If not, take more shots. ?????ÿ

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@norman-oklahoma?ÿ

I'm sorry, I seriously thought the poster wanted input. I'm trying to stay in my lane.

Posted by: @oldpacer

I'm sorry, I seriously thought the poster wanted input. I'm trying to stay in my lane.

Nothing wrong with your posting. It is me that is being irreverent. But I couldn't resist the opportunity.

@rover83 and @oldpacer

Thank you for the input. I agree that RTS is preferred, but in rural areas with no tree cover, I feel comfortable with the tolerances achievable from GNSS. Just trying to develop the best procedure to make efficient use of the tool.

If all you have is GNSS...

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Use the GNSS to set monument in the right place.

Make 'measurement of record' to the monument - two 60 second measures, with a 180 degree pole spin between

Go do something else for at least 30 minutes to get?ÿ a different constellation configuration. A re-initialisation is also a good idea

Repeat the 'measurement of record' as a check.

Can also repeat the checks with a different base location

Typically we will set all the monuments in the morning and then go back around them in the afternoon.

All the measurements, and averages of the pairs should be within your specified tolerances.

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Trimble are currently pushing a new feature where you divide your satellites into two groups - use one group for measurement of record, then immediately change groups (so constellation changes) and make your check measurements - not sure how much traction this is getting in the real world

@jimcox?ÿ

Some fly by nighters are saving a few $$ by skipping the second round of fixes but personally I'm just appreciating the extras sats all on so reliability of both rounds is slightly improved.

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NZ tolerances are greater on monuments (30mm max urban from control point that tied from and 60mm + 15mm/100m between boundary points) than the control 25mm + 5mm/100m) used to set them and recorded on the survey plan. Now any surveyor worth their salt would be aiming for closer to half those tolerances.

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My preferred setout is to stake position using instantaneous, place peg (50mm X 50mm x 500mm plastic) then shoot for 30 epoch+, adjust with hammer, shoot again, repeating till happy. Then double tie 30 mins+ later. If it's in seal/concrete, setout, shoot, adjust then temporarily mark with marker pen/crayon, double tie 30 mins+ later and if both agree then set nail/plug with boundary disk.

Posted by: @lukenz

My preferred setout is to stake position using instantaneous, place peg (50mm X 50mm x 500mm plastic) then shoot for 30 epoch+, adjust with hammer, shoot again, repeating till happy. Then double tie 30 mins+ later.

That's a good method for RTK-only.

Posted by: @jimcox

Trimble are currently pushing a new feature where you divide your satellites into two groups - use one group for measurement of record, then immediately change groups (so constellation changes) and make your check measurements - not sure how much traction this is getting in the real world

This actually works really well when you are running full-constellation receivers and have good sky visibility. Gives a mostly-independent solution without having to wait for the entire constellation to change. Repeatability has been very good.

The only problem we have had is crews not really understanding when and when not to employ this method.

@jimcox I just played with that feature on the sky plot. SvA SvB. Neat little feature. ?ÿ

I like how all of this care is taken, going back multiple times, checking things in the office, and so on.?ÿ And then 20 minutes after you leave the site a horse wanders over by the pin and happens to step on it, moving it 0.05.

@bstrand?ÿ

Or a fencing contractor removes it to put a post in then "puts it back in the same place"

My instructions tomy crews is not to useRTK that way.?ÿ We don't have a base/rover set up, it's all VRS.?ÿ I'm a firm believer in setting important points via TS.?ÿ I won't allow RTP to be used for many of the things that my crews would like to use it for, with the exception of open field topo, rough staking, staking soil borings, locating wetlands flags and similar items.?ÿ I don't want to waste my time processing and reprocessing.

Setup your base and rover for RTK, don't use network RTK.?ÿ

Use RTK to establish three control points in open sky near corner to be set.?ÿ

Setup instrument on RTK point. Check distances and angle between the RTK points.?ÿ If out of tolerance then take RTK back your truck and run an EDM traverse.

Posted by: @norman-oklahoma

Get a Javad. After setting the rod, record 5 shots on it. As long as 3 of them are within a 0.2'?ÿ radius of the stake coordinate you are golden.?ÿ If not, take more shots. ?????ÿ

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Except that's the exact opposite way that it works. You take one shot and it does the work of other software that would usually require collecting multiple shots and manually resolving them.

Posted by: @rover83

@norman-oklahoma?ÿ

Perfect

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If you are locating all the controlling corners by RTK then I don't see the need to use a Total Station on RTK control to set a monument.

We only use a local base.

We set the monument via RTK stake-out, then observe it at least twice at different times of the day like any other found monument.

But I'm the LS and I set my own monuments so instructing someone else to do it for me, I'm not sure how I would do that.

History is just repeating itself. When the EDM arrived. Everyone kept chaining distance with-a steel tape. The EDM was some magic no one trusted. After some education time and testing and learning where they worked what caused errors ?ÿand what did not : shooting distances to short aka less than 100 ft bad idea with some edmƒ??s some were designed for long distance not short the wavelengths determined the sweet spot. ?ÿPrism offset issues or constant, hills or terrain that delayed the signal. ?ÿNow we are seeing the same thing with GPS GNSS RTK network RTK. Lets see if we perform static work we can measure from one side of any state to the other very precise and accurate. Or I can achieve a Absolute Position any where in the world and do that many times and fit all the answers inside my coffee cup. RTK base and rover. ?ÿEvery one loves them for setting control points to begin a traverse and throw it back in the truck. Few have learned to utilize them to do most of the control where applicable and tolerance allowed to topo set rough stakes locations on some things. Others have really studied and tested and figured out how and when to use them 90% of the time for almost any application. I would say education is the key. Understand the gps constellation is the same today at 8 am as it will be tomorrow next week and a month later almost identical. The geometry is in the sky not on the ground. ?ÿ30 minutes it doesnƒ??t change much But it will provide a check on multi-path. 1 hr minimum on base and rover I might be wrong with full constellation now days but 4 hr minimum for network rtk. That gives you a more accurate position. ?ÿRemember like a edm thats when you push that measure command you measuring more than once. It might be 180 60 30 5 2 or 1. For control and property corners I like 180 still. Not as necessary as the old days. But I like it. I still at minimum will position a point then reset re initialize on that point. Or move away and get intialzed in a different environment and walk back do a quick visual ck. While i am there. Just to make sure i am good before headed on to my next point. Now this method goes back to the days where a receiver did no init checks for up to 15 minutes internally. Aka the 5800. But I believe the newer equipment all is almost in real time with this. But it never failed someone would get a bad init by the metal suburban walk to point measure place equipment back in suburban the. Come back at another time and be feet off. I have seen this happen 4 times on the R10 mod 1. Recently. Not enough time yet with R12 to determine for myself yet. But if you are running a base and rover and pay attention to snr. Elevation and azimuth of your equipment along with rms values and environment around you. I see know reason you cant use some good old fashioned surveyor procedures to locate or set a property corner. Move the base check it again. Almost like closing the horizon or double tying a point from two different set ups or back sites. I set 2 recently. I set to 5 ft offset nails one online one perpendicular. Located them at same time measures the 7.07 diagonal and as a check. Came back shot all again 4hrs network. Rtk. Had about .07 between on all 3. Split the difference. It was a 5/8 rod set. ?ÿ Now crew came behind me to check me with a robot. .02 difference. On one .035 ft on others roughly. They traversed with a 5ƒ? s6 multitrack prism and rod 1250 feet. So 3 set ups one angle. If we do the math for position error tolerance who is closer to truth. If this was a 80 x 100 foot lot survey i would not use it but 5 to 10 acres plus boundary or 100 to 500 acre boundary surveys. All day long rtk. With good procedures and checks. And lots of patience. I use gps in thick cannopy when i am solo instead of chaining down through to flag evidence look for corners set up traverse etc. i even locate the corners i find in differential mode. I take care to use a point number group and code so not to be used for the boundary resolution but to help the next crew find it as search points or whatever. If i was just dropping by to get them started. I donƒ??t care if i am off 10 feet although i have generally been less than 3. Locate trees blazed. Flag them. Some crews only look for metal objects. Old fence post they never see only new stuff. ?ÿLol so I might shoot a tope shot and flag that post or tree. Gps rtk static gnss total station robot transit chain tape pacing is all just tools. All have pros and cons. I say learn to push them until you find the breaking point the limits. Then you know when and how to use them. Teach your guys its ok to use them in hostel environments just document for recovery etc. i tried talking the boss to grab a handheld when goes and walks a property to bid. I say locate a point by the creek you need locate the old house foundation when you are out with the land owner. If we have to locate all of that plus boundary. We have a point and direction instead of us walking all around the interior because you saw an old well and want us to locate it near the swamp. Lol. All of that extra stuff just needs to be managed so not to be used as survey grade. ?ÿ