I'm looking for input on accepted procedures to set a boundary corner by way of GNSS. What are your instructions to crews?
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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I'm sorry, I seriously thought the poster wanted input. I'm trying to stay in my lane.
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.
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.
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.
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.
