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Preparing for the 2022 datum
Posted by bigd1320 on January 1, 2022 at 4:46 pmI spoke with a county engineer who is reviewing a proposal for the county HARN adjustment for the new datum by another vendor. I assume the vendor is preparing for the new datum release and wants to gather data on the passive marks ahead of that time. I assume those passive marks have not been occupied since the early 2000’s.
With that said we discussed what will happen to the RTN when we move to the new datum in the future. I am working my way through Blueprint No. 3 and I’m still trying to figure things out. For now we’ll do a wholesale change like we did for NAD83, but that is just a guess.
What I think will happen for the county surveyor is there will be a shift in their control points if he doesn’t transform the data from NAD83 and NATRF2022. The easiest way I could explain this was to relate it to a back sight. If your coordinates on your back sight (and occupied point relatively) were 5000.00, 5000.00 and you changed them to 5001.00, 5001.00 you’ll see a shift in the rest of the points you want to stake out.
Does this simple explanation sound correct?
I have many novice surveyors who either are unaware of this change or don’t understand it. I how to educate as many RTN users I can so they are prepared for the new datum. So far the best advice I can give is to document well what datums and adjustments you are using now. That way in the future tools will be available to us to work back and forth.
MightyMoe replied 2 years, 2 months ago 20 Members · 89 Replies- 89 Replies
- Posted by: @bigd1320
What I think will happen for the county surveyor is there will be a shift in their control points if he doesn’t transform the data from NAD83 and NATRF2022. The easiest way I could explain this was to relate it to a back sight. If your coordinates on your back sight (and occupied point relatively) were 5000.00, 5000.00 and you changed them to 5001.00, 5001.00 you’ll see a shift in the rest of the points you want to stake out.
No, it will not be just a few feet difference in the coordinates. It will likely be 100’s of thousands of feet different in the coordinates. This way there is no confusion of datums.
A point can have NAD27 coordinates and NGVD29 elevation, NAD83 coordinates and NAVD88 elevation, assumed coordinates and elevation, or whatever. A transformation can be done between them at some level of accuracy.
NGS is working on making a good transformation tool from NAD83(2011) to the 2022 datum. When that is released we can hope transformation elevations to be within a couple cm of what you measure with GNSS (+ geoid) in the new datum. Here in Iowa we will have a decent transformation accuracy, but not as good as MN and WI because of the density of their measurements. Except for the GSVS14 run, the data to check the transformation is somewhat sparse in Iowa. You can contribute to the accuracy of that new transformation by submitting GPSonBM sessions in areas that have gaps.
https://geodesy.noaa.gov/GPSonBM/
I believe the 2022 horizontal coordinates in Iowa will be expressed in the same zones as the present Iowa Regional Coordinate System, with new false northings and eastings.
@norm Miller has a better handle on it than I do.
.I thought I heard, somewhere, that the 2022 datum had been postponed ???? until 2025
I’ll Google it and get back to you ???
I hope everyone has a great day; I know I will!- Posted by: @dougie
I thought I heard, somewhere, that the 2022 datum had been postponed ???? until 2025
I’ll Google it and get back to you ???
That is my understanding as well
It’s true from what I was told and been exposed to, but that doesn’t mean they haven’t been working hard behind the scenes to get it back on track.
Here the link back to March 2021 when we submitted our process for the cause.
They are talking about 2024-2025 bu of course that’s just an estimate.
https://geodesy.noaa.gov/datums/newdatums/FAQNewDatums.shtml
.I plan to retire in early July, then shift to doing consulting work to help entities make this transition. For sure all the GPS on BM submissions will help improve the accuracy of the NGS transformation tools, but a lot of passive marks will be left behind. If they haven’t been included in a NGS bluebooked project in the past 20 years or so, they likely will not have published values in the new NSRS. All the HARN/HPGN networks predate that cutoff. If they are important to your work, at least perform observations compliant with the OPUS Share requirements and submit them. Even better, process them through OPUS Projects and get them updated in the NGS integrated database (the “new” bluebooking).
Although just math, the change from the US Survey foot to the International foot in the 40 states that will have to deal with it when bringing legacy data forward will require a well documented workflow.
The geodetic shifts will be on the meters level, but the State Plane Coordinate shifts will be very large for reasons stated previously.
How the “pay for play” RTN operators deal with this is another matter. Most state run RTN systems will/should be prepared. And yes, if anyone is already theoretically prepared for it, it would be Gavin.
- Posted by: @spmpls
Although just math, the change from the US Survey foot to the International foot in the 40 states that will have to deal with it when bringing legacy data forward will require a well documented workflow.
Have all states actually established legislation for a change to iFt?
NGS has deprecated the USFt, but states could still mandate it if they really wanted to. That would be a bad idea, but it’s still possible, and there’s still a lot of resistance to standardizing with international feet.
Genuinely curious, since I don’t know of a way to track that aside from monitoring legislative bills and updates to statutes for each state.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman - Posted by: @rover83
Have all states actually established legislation for a change to iFt?
No, easier said than done.
We are going for administrative rules written to follow the lead of whatever the current NGS policy is so no future legislation changes will be needed when new policy, datum, etc etc occur. Ironically, we legislated a change from Ift to US ft. not so long ago. Now we are headed back to where we started. We went to US ft. because no one was following the I ft. law. If you can’t beat em, join em.
- Posted by: @bill93
I believe the 2022 horizontal coordinates in Iowa will be expressed in the same zones as the present Iowa Regional Coordinate System, with new false northings and eastings.
Correct. Same zone boundaries expressed in even meters on the origins and not close to the current US ft values when converted. The official zone coordinates will be meters so any conversion to I ft or US ft will be up to the end user. When the user converts 2022 metric coordinates to I ft or US ft. it will be millions of ft different then what the current value is.
disclaimer: anything I state may not be current since I am no longer NGS state coordinator.
California, where I practice, will have to change the laws to accommodate the new reference frame/datum/State Plane coordinate system through the legislative process, as we don’t have the administrative rules option Norm mentioned. The definition of the International ft as the “official foot” for the new SPCS will be included in that effort.
It will be interesting to see if any states actually retain the US Survey ft. for their SPC2022 system. I have heard it said that because this was done by NIST (https://www.nist.gov/), it would be akin to a state deciding to not recognize the Federally established unit of money. The Feds could eventually put a squeeze on nonconforming states by withholding federal funds for transportation or other purposes.
@spmpls I don’t know about the feds pressure…they tried that with the meter (i.e. the US going metric) and the DOT in my state spent millions of $$$ updating manuals, etc but then the feds backed off. Big shame, then we would not be having this conversation about which foot to use.
What datum are the local FEMA maps on?
That’s the datum I’ll be on.
I agree, but I have heard the “what-ifs” for non-compliance.
Oregon’s coordinate system is governed by Administrative Rule so updating them is much simpler.
Washington has turned the control of its zone systems over to the NGS, so whatever they dictate goes.
- Posted by: @norman-oklahoma
Oregon’s coordinate system is governed by Administrative Rule so updating them is much simpler.
Yes, I wish we had that option so our DOT could just take care of the updates.
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