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Our delta was about 5 inches higher going from 29 to 88.
Roughly 1/2 foot is what it is in Oklahoma as well.
’88 is 3-1/2 feet greater than ’29 here in Beaverton, Oregon.
MightyMoe is right on – we will all likely be dust and long forgotten before FEMA does anything systematic about updating the maps. Regrettably the agency has almost no one who can even spell the word datum much less really know what it means, they rely on their contractors to take care of that menial suff!! All too often I’ve found that any number of their contractors know only slightly more than FEMA does. The conversations I’ve had with FEMA over the years about how they will handle the North American-Pacific Geopotential Datum 2022 is that they will rely completely on the NGS developed vertical transformation tool. I hope surveyors across the country will take a seriously hard look at the Web Map on the NGS GPS on BM page – https://geodesy.noaa.gov/GPSonBM/. While NGS will likely accept additional observations until the total network cutoff 2/29/24, I suspect it will probably be minimal from what’s already there. Therefore, you can make some pretty good assumptions about what the actual accuracy of that transformation tool will be by looking at the number of requested stations that have NOT been submitted. States/Territories like CT, DE, MA, MN, NJ, NC, PR, VT, WI will likely be relatively accurate at the couple of cm/.1 ft level. With some regional exceptions in a few states the actual uncertainty in the rest of the country is going to be higher, could be in the 4-6 cm/.2 ft range, perhaps more. If requirements are to stay on NAVD 88 at a tolerable level say .1 ft this might be complicated without directly connecting to NAVD 88 passive control when you also consider the additional uncertainty in any surveyors’ ellipsoid height accuracy. Unfortunately the vast majority of surveyors have paid little attention to the NGS requests for data to address this issue so it will be what it will be.
Unfortunately the vast majority of surveyors have paid little attention to the NGS requests for data to address this issue so it will be what it will be.
While there certainly could have been more data gathered, it’s not even remotely accurate to pin this problem on “surveyors”. This is a national issue with significant economic consequences. If federal, state, or local governments thought it was important enough, they could have implemented programs beyond “hey surveyors, go spend your time, money and resources on this critical thing in your off-hours, because we said so“.
Hats off to the NGS for spearheading the effort, and hats off to all the surveyors who did contribute. I’m impressed that we got as much data as we did. But it was still a volunteer effort, across the entire country.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil PostmanThe days of NGS having any meaningful field force have been gone for decades due to the development of GPS technology. What they use to do at the local level has long since been taken over by the local government and the private side. When I said surveyors I meant across the board not just the private sector. You can easily see the support that state government surveyors gave if you look at the list of states I indicated looked pretty good. The entire requested set of stations in Puerto Rico was observed by private surveyors. While NGS certainly understands the importance of datum transformation tools, with the exception of ITRF to NAD 83 they play virtually no role in the development and enhancement of the National Spatial Reference System. These are tools that have the greatest importance to agencies and groups that manage legacy data.
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